7/12/83
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`Umted States Patent 119]
`Gresser et al.
`
`111]
`[45]
`
`4,392,476
`Jul. 12, 1983
`
`[54] METHOD AND APPARATUS FOR PLACING
`IDENTIFYING INDICIA ON THE SURFACE
`0F PRECIOUS STONES INCLUDING
`DIAMONDS
`[75] Inventors: Herbert D. Gresser, Plainview;
`George Kaplan, Port Chester; Joseph
`Nussenbaum, New York, all of NY.
`[73] Assigneez Laure Kaplan & sons, Inc.’ New
`York, NY.
`[2]] Appl. No.: 220,195
`_
`_
`[22] Filed‘
`Dec‘ 23’ 1980
`[51] Int. Cl.3 ............................................. .. B28D 5/00
`[52] U S Cl
`/ 215 “32/12?
`[58] Field Of Search ..................
`125/30 R; 63/32;
`‘
`219/121 L, 121 LM
`
`.. . ................................... ..I2530R-6
`
`-
`
`_
`References Cited
`U.S. PATENT DOCUMENTS
`2,293,100 8/1942 Baumgold ....................... .. 125/30 R
`2,332,574 10/1943 Hopp ........ ..
`3,627,858 12/1971 Parts .......................... .. 219/121 LM
`
`[56]
`
`4,056,952 11/1977 Okude ................................... .. 63/62
`411431544 3/1979 Dev?es 6131' ~
`-
`4,156,124 5/1979 ' Macken ......................... .. 219/121 L
`FOREIGN PATENT DOCUMENTS
`377326 7/1979 Belgium _
`130318 3/1978 German Democratic Rep.
`R
`133023 11/1978 RGerman Democratic Rep.
`-
`
`125/30
`
`125/30
`
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`dL 0
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`ptics an
`user ec no ogy, “ rintingo Part Numbers
`using High Power Laser Beam”, pp. 256-265, Dec.
`1973.
`Primary Examiner-—Harold D. Wh1tehead
`[57]
`ABSTRACT
`,
`_‘
`'
`_
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`A pract1ce for applymg indicla to the surface of a pre
`cious stone wherein a source of laser energy is directed
`at the stone surface and controlled to inscribe the sur
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`U.S. Patent
`
`Jul. 12, 1983
`
`4,392,476
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`1
`
`METHOD AND APPARATUS FOR PLACING
`IDENTIFYING INDICIA ON THE SURFACE OF
`PRECIOUS STONES INCLUDING DIAMONDS
`
`4,392,476
`2
`following detailed description in conjunction with the
`accompanying drawings in which:
`FIG. 1 illustrates in block diagram form a system for
`providing indicia to a precious stone in accordance with
`the principles of the present invention;
`FIG. 2 illustrates the matrix of positions to which the
`laser beam of the system of FIG. 1 can be directed;
`FIG. 3 shows a laser beam locations de?ning a typical
`indicium which can be inscribed utilizing the system of
`FIG. 1.
`
`H LII
`
`20
`
`BACKGROUND OF THE INVENTION
`This invention pertains to handling of precious stones
`or gems and, in particular, to a method and apparatus
`for placing indicia on the surface of such stones.
`In the handling of precious stones, it is common prac
`tice to categorize the stones in terms of various charac
`teristics. Thus, for example, diamonds typically are
`categorized in terms of color, weight, degree of perfec
`tion and vendor. Since these categories control the
`value of a stone, it is essential that they follow the stone
`through its travel from the original vendor to the even
`tual purchaser. Heretofore, however, it has not been
`possible to indelibly mark or place this information
`directly on the stone without defacing it and, therefore,
`reducing its value. As a result, the information must be
`communicated apart from the stone at the time of trans
`fer. This practice is not without risk, since there is al
`ways a possibility that the information might be lost or
`misplaced or purposely misrepresented. In the case of
`lost or misplaced information, recategorization would
`have to be'carried out at considerable expense in equip
`ment, and manpower in order to reestablish the stone
`value. Purposely misrepresenting the information, on
`the other hand, could result in a defrauding of the pur
`chaser.
`It is therefore an object of the present invention to
`provide a practice for placing indicia on a precious
`stone in a manner which preserves the value of the
`stone.
`vIt is a further object of the present invention to pro
`vide a system and apparatus for placing identifying
`indicia on a precious stone such that the indicia cannot
`be removed without reducing the value of the stone.
`
`DETAILED DESCRIPTION
`In FIG. 1, a laser beam generation system 2 applies a
`pulsed laser beam 3 to a diamond 5 for the purpose of
`inscribing an indicium or a plurality of indicia in the
`diamond surface 4. The indicia can be of any type such
`as, for example, numbers, letters, words, decorative
`patterns, trademark symbols, portraits, images, signets,
`coats of arms, names, family crests, etc. Furthermore,
`the indicia can be indicative of the above-mentioned
`categories of information (color, weight, degree of per
`fection, vendor) related to the diamond value.
`As shown, the surface 4 is what is commonly referred
`to as the “girdle” of the diamond. However, it should be
`pointed out that the principles of the invention are ap
`plicable to incription of indicia in any surface of the
`diamond 5. Similarly, the principles of the invention are
`applicable to inscription of precious stones other than
`diamonds, although the practice of the invention is
`particularly bene?cial for diamond inscription due to
`the ability of laser radiation to penetrate the hard
`diamond surface.
`Application of the laser beam 3 to the surface 4 is
`controlled by an optical system 6 which is situated be
`tween the beam generation system 2 and the diamond 5.
`The optical system 6 positions and controls the beam 3
`such that the beam is able to inscribe or engrave the
`surface 4 and produce an indelible indicium which sub
`stantially preserves the value of the diamond and
`which, if removed, would appreciably reduce such
`value.
`In accordance with the invention, the expanse of the
`beam 3 at the surface 4 having suf?cient intensity to
`inscribe the diamond 5 (referred to hereinafter as the
`“beam scribing width") is maintained at approximately
`100 microns or less so as to produce an indicium of
`similar width and, therefore, one imperceptible to the
`human eye. While all beam widths within the aforesaid
`‘range are useable with the invention, it is perferable to
`select the beam scribing width such that the resultant
`indicium can be readily observed with magni?cation
`equipment presently used by jewelers in the industry.
`Thus, a beam scribing width resulting in an indicium
`capable of being read by a conventional ten (10X)
`power magnifying loupe would be bene?cial, as this
`loupe is one that is commonly used in the trade. The
`optical system 6 provides beam scribing widths of the
`desired expanse by focusing the beam 3 and by ensuring
`that the beam is positioned during inscription such that
`the surface area being inscribed is within the depth of
`?eld of the focused beam.
`A table system 7 supports the diamond 5 and is ad
`justed to maintain the surface 4 of the diamond at the
`beam 3 focus position during the inscription process.
`The latter table system, as well as the optical system 6
`and the laser generator 2 are sequentially controlled by
`a computer control system 8.
`
`25
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`30
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`35
`
`SUMMARY OF THE INVENTION
`In accordance with the principles of the present in
`vention, the above and other objectives are realized in a
`practice wherein an identifying indicium is placed on a
`precious stone through application to the stone surface
`of a beam of laser light which is so controlled as to
`45
`scribe in the stone surface the desired indicium. Use of
`a laser beam enables realization of extremely small
`scribing beam widths so as to result in an indicium
`which is imperceptible to the human eye. Loss of value
`of the stone is thus substantially avoided, while an indel
`ible and integrated identi?cation is created in the sense
`that removal of the indicium could not readily be car
`ried out by most people handling the stone and would
`necessitate recutting of the stone to an extent which
`would result in a loss in value.
`In the practice of the invention to be disclosed herein
`after, the precious stone being inscribed is a diamond.
`The laser beam is focused on the diamond surface and is
`scanned over a path de?ned by the indicium to result in
`the desired inscription. Also, in the disclosed embodi
`ment, at the start of each inscription, the energy of the
`beam imparted to the diamond is suf?cient to cause
`graphitization. The remainder of the inscription is then
`able to be effected at lesser power.
`
`55
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The above and other features and aspects of the pres
`ent invention will become apparent upon reading the
`
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`normally opened safety shutter 26 is provided in the
`The table system 7 includes four tables 71, 72, 73 and
`path of the beam'3 forward of the Q-switch 22, the
`74 which are stacked one on the other and which to
`shutter 26 being closed upon micro-processor 85 gener
`gether are mounted on a stationary support or frame 75.
`Each of the tables 71-74 enables a particular mode of
`ating a signal indicating an unsafe condition in the sys
`movement of the diamond 5. Translational movement
`tern.
`along the x and y directions of a mutually orthogonal
`Passage of the beam 3 through the safety shutter 26
`coordinate system x,y,z is effected by tables 71 and 72,
`brings the beam to the optical system 6. A first scanner
`respectively, the x and y directions being horizontal
`or de?ector 61 is adapted to de?ect the beam in inter
`directions into and in the plane of the drawing respec
`mittent or digital fashion in the x-direction. Following
`tively. The diamond 5 is rotated about the z direction (a
`the de?ector 61, is a beam expander 62 which expands
`vertical direction in the plane of the drawing) by opera
`the beam 3 prior to entry into a second scanner or de
`tion of the table 73. The ?nal movable table 74 provides
`flector 63 which is adapted to de?ect in intermittent or
`further translation of the diamond in the y direction.
`digital fashion the beam in the z-direction. A second
`Stepping motors 76, 77, 78 and 79 drive the tables
`beam expander 64 follows the deflector 63 and conveys
`71-74, respectively, and, in turn, receive analog activa
`the beam to a variable attenuator 65 which sets the
`tion signals from drive elements 81-84 of computer
`relative intensity or power of the beam before the beam
`control system 8. These drive elements are addressed
`impinges upon a focusing means in the form of an objec
`automatically by signals from a control micro-processor
`tive lens 66. The latter lens focuses the beam 3 at a point
`85 or manually by a joy stick control system 86. Posi
`adjacent the surface 4 of the diamond 5.
`tional feedback signals also are fed to the drivers from
`Control of the x and z scanners 61 and 63 is through
`their respective tables.
`x and 2 RF scan generators 69 and 70 which, in turn, are
`Useable components for the tables 71 and 72 might be
`addressed by signals from the micro-processor 85. The
`tables manufactured under model number DC-33 by
`x scan generator also provides on-off control of modula
`Design Components Incorporated. Tables manufac
`tor 61’ likewise based on signal control from the micro
`tured by the latter manufacturer under model numbers
`processor.
`RT-60l and LP-35 might be used for the tables 73 and
`Typical components for the scanners 61 and 63 might
`74, respectively. The motors 76-79 might, in turn, be
`be acousto-optic de?ectors of the type manufactured by
`model number 49FG motors manufactured by PMI
`Intra-Action Corporation under model number ADM
`Motors.
`70. The scan generators 69 and 70, in turn, might be
`A memory 87 of the computer control system 8 stores
`components designated DE-70M and manufactured by
`instructions and data (e.g., special and standard indicia
`the same company.
`instructions and data) for carrying out the inscription
`Prior to inscription of indicia on the diamond 5, an
`process. This information is processed by the micro
`initial procedure must be carried out to provide the
`processor 85 to develop the necessary signals for se
`computer system 8 with information as to the indicia
`quentially controlling operation of the laser generation
`35
`length and the geometry of the surface 4. The latter
`system 2, optical control system 6 and table system 7. A
`surface can take on various forms and might comprise
`keyboard unit 88 permits entry of operator control in
`plane surfaces (facets) connected by edges or it might be
`structions, including instructions defining the particular
`a continuous surface with or without curvature. The
`indicia to be inscribed. A system display 89 enables
`indicia and surface geometry information enables the
`keyboard data to be displayed to ensure correct entry
`computer system to develop, via calculation subpro
`and allows prompting of the operator during system
`grams stored in memory 87, the necessary signals for
`operation.
`controlling the table system 7 to properly index the
`A Rockwell 6502 microcprocessor might serve as to
`diamond 5 and to bring successive regions of surface 4
`micro-processor system 85, while the memory 87 might
`into confronting relationship with the beam 3 at the
`comprise a PROM section (for special indicia informa
`point of focus thereof. Viewing microscopes 101 and 68
`tion) in the form of two 2708 ultraviolet programmable
`mounted above and in front of the diamondS are pro
`read-only memories and a ROM section (for standard
`vided as an aid to obtaining this information. As shown,
`indicia information). The display 89 might include a
`microscope 101 permits direct viewing of the diamond
`6543 Rockwell controller providing instructions to a
`from the above, while microscope 68 permits viewing
`CIOTO monitor. Each of the drivers 81-84 might in
`the diamond frontally via beam splitter 67.
`clude 74193 bi-directional counters and digital-to
`Discussion of this initial procedure will be in the
`analog converters (DAC-BO) having 12 bits of resolu
`context of the surface 4 being at the girdle of the
`tion.
`diamond 5, but the procedure can be readily adapted to
`Turning to the laser generator 2, a continuous laser
`other surface areas. The operator begins the procedure
`source 21 applies the laser beam 3 to a Q-switch 22
`by introducing into the memory 87, via the keyboard
`which is varied in state to allow high peak power pulses
`88, a code indicative of the indicia to be inscribed. The
`of the beam to pass to the optical system 6. Q-switch RF
`micro-processor 85 is thereupon initiated again by key
`pulse generator 23 establishes the state of Q-switch 22 as
`board operation to calculate and store in the memory
`a function of signals from the micro-processor 85.
`87, the total length encompassed by the entered indicia.
`A frequency multiplier 25 is interposed between laser
`The diamond is then viewed with the microscope 68
`21 and Q-switch 22 in order to increase the frequency of
`and the diamond ?xture (now shown) is moved along
`the laser radiation and, therefore, obtain radiation of
`reduced wavelength. This permits obtaining smaller
`the z direction by a micrometer (not shown) to first
`align the upper and then the lower girdle edges with the
`beam scribing widths at the surface 4. Typically, if a
`microscope horizontal cross-hair. The difference in the
`Nd-YAG laser at 1.06 microns were used as the laser 21,
`micrometer readings at these alignment positions is then
`the multiplier 25 might be a frequency doubler, if beam
`taken by the operator who enters same via keyboard 88
`scribing widths in the range of l to 100 microns were
`desired. To complete the laser generation system, a
`into the memory 87.
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`The operator then views the diamond from above
`this case, however, if the inscription length exceeds the
`with the microscope 101 and operates the joy stick
`length of the facet, or if a character falls on a facet
`intersection, the micro-processor 85, having stored the
`control 86 to move the,tables 71 and 72 to displace the
`intersection locations, will signal the table system 7 to
`diamond in the x and y directions such that a point on
`the pro?le of the girdle is brought to the intersection of
`bring the next facet into position in a similar fashion as
`the cross-hairs of the microscope. When performing
`the previous facet.
`.
`Once the above initial procedure is completed, the
`this operation, if the operator views one or more facet
`edges, the operator enters via the keyboard 88 a code
`system is ready to inscribe the surface 4 of diamond 5
`indicating to the micro-processor that the information
`with the entered indicia. Inscription is initiated by the
`operator again activating the keyboard 88.
`being introduced is to be analyzed with a sub-program
`adapted to faceted surfaces and stored in the memory
`The operator also turns on the power supply and
`cooling system 24 to bring the laser 21 into operation.
`87. If the operator views no facet edges, indicating a
`Signals are then provided by the micro-processor to the
`continuous surface, then no entry is made and the mi
`cro-processor will then automatically analyze the intro
`generators 69 and 70 to condition the digital scanners 61
`duced information with a sub-program adapted to
`and 63 to provide given amounts of x and z de?ection to
`curved surfaces. Having conditioned the micro-proces
`the beam 3. In the case of acousto-optic de?ectors, this
`sor regarding the type of sub-program to be used based
`would amount to establishing in each de?ector an
`on the surface, a keyboard store key is depressed and
`acoustic disturbance at a radio frequency associated
`the locations of tables 71 and 72 are conveyed from the
`with the desired amount of beam de?ection.
`respective drive elements, via micro-processor 85, to
`As can be appreciated, the generators 69 and 70 and
`de?ectors 61 and 63 de?ne an array of positions, shown
`the memory 87.
`_
`_
`The operator then again operates the joy stick control
`in FIG. 2, to which the beam 3 can be de?ected. The
`present excitation signals delivered by the micro
`to move tables 71 and 72 and bring a further point on
`the girdle to the intersection of the cross-hairs. The type
`processor 85 to the generators, in effect, select one of
`these positions, which is the beginning position for the
`of the control exercised in this operation depends upon
`present inscription.
`which sub-program is in effect. If the sub-program
`The generator 69 also delivers a signal to key the
`adapted to curved surfaces is in use, the table 71 is ?rst
`modulator 61' on/off. In the present illustrative case,
`moved to provide a ?xed x displacement to the
`diamond. This is followed by operation of table 72 to
`this signal places ‘the modulator in the full on condition;
`thereby allowing the beam 3 to pass at full intensity.
`provide a y displacement sufficient to bring the further
`Such intensity is suf?cient to result in the focused beam
`point into coincidence with the cross-hairs. If the sub
`3 inscribing the- surface 4 in the area covered by the
`program adapted for faceted surfaces is in use, move
`inscribing beam width. Typically, for most applications,
`ment of the tables provides x and y displacement suffi
`cient to bring the edge of the next facet to the intersec
`the power in beam 3 as it exits variable attenuator 65
`might be in the range of 0.5 to 5 kW, the particular
`tion of the cross-hairs. Once the further surface point is
`value used, amongst other things, being dependent upon
`brought to the cross-hair intersection, the table dis
`the scan rate and pulse rate of the beam 3. A typical scan
`placements are again entered into the memory 87.
`rate might be 1 millimeter per second and a typical pulse
`The aforesaid procedure of moving the tables to
`place additional points of the girdle pro?le at the inter
`rate 1 kHz.
`Having established the initial de?ection conditions
`section of the microscope cross-hairs and the storing the
`and the appropriate modulator condition, the micro
`table displacement is continued until the sum of the
`facet lengths exceeds the previously stored indicia total
`processor 85 now signals the generator 23 to operate
`length. This is automatically calculated by the micro
`Q-switch 22 and thereby allow passage of the beam 3
`through the optical system 6 to the surface 4 of the
`processor and displayed on the display 89.
`diamond 5. During such passage, the beam 3 is de?ected
`At this point, the micro-processor has all the neces
`by respective scanners 61 and 63, allowed to pass at full
`sary data needed regarding the indicia and diamond
`intensity by the variable attenuator 65, and brought to
`surface geometry to properly orient the diamond. In the
`focus on the surface 4, whereby, as shown in FIG. 3, a
`case of curved surfaces, the entered data is utilized by
`?rst elemental area A] of the surface is inscribed.
`the sub-program to derive the radius of curvature and
`center of rotation of the surface. The tables 71, 72 and
`Thereafter, the de?ection amounts are indexed based
`50'
`upon the micro-processor 85 indexing the signals to the
`74 are thereupon moved to place the center of rotation
`generators 69 and 70 pursuant to the program in the
`at the center of rotation of the table 73 and to place a
`memory 87 and the Q-switch is operated, resulting in
`starting point on the girdle at the focus point of the
`beam 3. In the case of a faceted surface, the entered data
`subsequent elemental areas A2, . . . ANbeing inscribed in
`is utilized to determine the intersection angle of the
`the surface 4 until the desired indicium, shown as an A
`in FIG. 3, is completed. The micro-processor 85 then
`facets. The tables are thereupon moved to place a fac
`signals the pulse generator 23 to again close the Q
`eted surface orthogonal to the axis of the beam 3 and to
`switch 22, thereby inhibiting further impingement of
`’ place a point on such surface adjacent the facet edge at
`the beam 3 on the diamond surface.
`the beam 3 focus.
`If the original operator instructions required further
`Having positioned the diamond as above-described,
`indicia to be inscribed, the micro-processor 85 addresses
`based on the geometry of the surface 4 and the indicia
`the appropriate driver element (81 for faceted surfaces
`length, subsequent indexing of the diamond for indicia
`and 83 for curved surfaces) causing same to actuate its
`inscription can now be readily carried out by the micro
`respective motor and its corresponding table. The
`processor controlling the table system 7. In the case of
`diamond 5 is thus indexed to bring a non-inscribed area
`curved surfaces, this indexing amounts merely to rota
`65
`of the surface 4 to the focus point of the beam 3. After
`tion of the table 73 to bring a non-inscribed area to the
`such indexing, the micro-processor again signals the
`beam 3 focus. For faceted surfaces, translational move
`generators 69 and 70 to establish de?ection amounts in
`ment of table 71 brings such area to the beam focus. In
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`the scanners 61 and 63 for situating the beam 3 at a ?rst
`As a result, when inscribing diamonds of this character,
`position de?ning the start of the second indicium. The
`it is desirable to apply an energy absorbing material
`pulse generator 23 is then addressed by the micro
`such as, for example, a liquid suspension of carbon
`processor 85 operating Q-switch 22 which allows pas
`black, to the surface 4 prior to inscription. Once this
`sage of the beam 3. Inscription of a ?rst elemental area
`material dries, subsequently applied laser energy will be
`of the second indicium results. Subsequent indexing of
`absorbed and inscription can then be more successively
`the generators 67 and 68 as above-described, results in
`carried out.
`the production of the desired second indicium on the
`Once inscription of the diamond 5 has been com
`pleted, the operator using microscope 68 and oblique
`surface 4. Further indicia are then inscribed in the same
`illumination can view the surface 4 to see whether the
`manner.
`As can be appreciated from the above description, the
`inscription was correctly carried out. In this way, if an
`Q-switch 22 remains operational after each elemental
`indicium is not inscribed, the operator can communicate
`this to the computer control system 8 and the system 8
`area (A1, A2 .
`. . AN) is inscribed and remains opera
`tional when the system is conditioned to inscribe the
`can return to the area of the diamond and inscribe the
`required indicium.
`next elemental area. As can be further appreciated,
`when the next elemental area is at the beginning of the
`It should be pointed out that the present inscription
`next indicium, the Q-switch remains closed for a longer
`practice is believed to be highly advantageous in that it
`time than if the next area were on the same indicium. As
`not only does not diminish the value of the diamond 5,
`a result, the pulse of beam 3 delivered to each ?rst
`but, in fact, adds value to the diamond through the
`inscription elemental area (for example A1) is of greater
`inscribed indicia. Thus, for example, inscription of the
`energy than the later pulses delivered to subsequent
`origin of the diamond (i.e., the vendor name or trade
`areas of the same indicium. This higher energy pulse at
`mark), enables the diamond to be easily identi?ed,
`the beginning of each inscription provides a needed
`thereby protecting the diamond against loss or theft.
`initial graphitization of the diamond surface. This
`Likewise, indicia indicative of the diamond value, pre
`graphitization, in turn, conditions the adjacent surface
`vent misrepresentation of such value, thereby affording
`protection against possible fraudulent practices.
`area so that it is now able to better absorb laser energy.
`The lesser energy pulse which follows the initial pulse
`In all cases, it is understood that the above-described
`and confronts this adjacent area is thus able to graphi
`arrangements are merely illustrative of the many possi
`tize and inscribe such area. In doing so it overlaps and
`ble speci?c embodiments which represent applications
`conditions its subsequent surface area which, upon re
`of the invention. Numerous and varied other arrange
`ceipt of the next pulse, is also now able to be graphitized
`ments can readily be devised in accordance with the
`and inscribed. This process of conditioning a surface
`principles of the present invention without departing
`area followed by graphitization and inscription of same
`from the spirit and scope of the invention. For example,
`by the lesser energy pulses continues until the indicium
`if the system requirements dictate that the Q-switch 22
`inscription is completed.
`cannot be operated to produce an initial pulse suf?cient
`In order for graphitization to occur on the ?rst pulse
`to cause graphitization, the latter can be effected by
`after operating the Q-switch 22, as above-described, the
`allowing not only the high energy initial pulse but also
`energy of this pulse ‘has to be at an appropriate level.
`one or more lesser energy pulses to impinge upon the
`Consequently, micro-processor 85 should maintain the
`initial surface area to be inscribed. In such case, the
`Q-switch closed between inscriptions for a length of
`micro-processor 85 would control the scanners to hold
`40
`time suf?cient to result in an initial pulse of such energy
`their deflection states until the desired number of pulses
`or greater. In the case of a Nd-YAG laser, this would
`impinge upon the surface area. If desired, subsequent
`mean maintaining the Q-switched closed for approxi
`surface areas also may be confronted by more than one
`pulse by using a similar practice.
`mately 1 or more milliseconds.
`Furthermore, when inscribing an indicium requiring
`What is claimed is:
`movement of the beam 3 to an elemental area removed
`l. A method for providing an identifying indicium to
`from a previously inscribed elemental area, (i.e., to a
`a diamond comprising:
`.
`non-adjacent elemental area), an initial graphitization
`applying a laser beam to a surface of said diamond;
`similar to that at the start of the inscription is again
`and controlling said laser beam to enable said laser
`needed. As a result, a similar high energy pulse is re
`beam to inscribe into said diamond surface an indi
`cium including:
`quired. The micro-processor 85 at these transitions thus
`also ensures that Q-switch 22 is closed for a long enough
`intermittently moving said laser beam to successive
`time that the next laser pulse has suf?cient energy to
`positions on said diamond surface along a path
`provide graphitization.
`corresponding to said indicium, said beam at each
`As above-described, the stepping of the beam 3 to
`position covering a diamond surface area overlap
`inscribe areas of the surface 4 de?ning a given indicium
`ping the diamond surface area covered by the beam
`is such that successively inscribed elemental areas (A1,
`at the immediately preceding position on said indi
`A2, for example) overlap. This overlap further ensures
`cium;
`that the beam 3 will graphitize and inscribe the succes
`and adjusting the laser beam power to graphitize and
`sive areas. It also results in an inscription which is sub
`inscribe said diamond surface at each of said posi
`stantially uniform and, therefore, easily readable with
`tions.
`the appropriate magni?cation. A useable overlap for
`2. A method in accordance with claim 1 wherein: said
`which such uniform condition pertains is about 85 per
`indicium is indelible.
`3. A method in accordance with claim 2 wherein: said
`indicium is of any preselected character.
`4. A method in accordance with claim 2 wherein: said
`indicium is indicative of the origin of said diamond,
`whereby said diamond can be identi?ed if stolen or lost.
`
`It should be pointed out that, in the case of some
`ultra-clear or highly polished diamonds, an initial Q
`switched pulse of the above-described magnitude might
`still not result in graphitization of the diamond surface.
`
`cent.
`
`.
`
`60
`
`65
`
`6
`
`

`
`15
`
`25
`
`4,392,476
`10
`5. A method in accordance with claim 2 wherein: said
`diamond about said point to bring each non-inscribed
`indicium is indicative of the value of said ‘diamond,
`area into confronting relationship with said beam,
`whereby said value cannot be misrepresented.
`whereby said beam is maintained in focus on the succes
`6. A method in accordance with claim 5 wherein: said
`sive areas of said surface being inscribed.
`indicium is indicative of one of the color, weight, de
`23. A method in accordance with claim 19 further
`gree of perfection and vendor of said diamond.
`comprising: prior to initially orienting said diamond,
`7. A method in accordance with claim 1 wherein:
`moving said diamond to at least three positions for
`controlling of said laser beam is such that said inscribed
`which said surface is at the point to which said beam is
`indicium is of a character which substantially preserves
`to be focused and calculating from said positions the
`the value of said diamond.
`center of rotation and radius of curvature of said sur
`8. A method in accordance with claim 1 wherein:
`face.
`controlling of said laser beam is such that said inscribed
`24. A method in accordance with claim 21 wherein:
`said method further includes initially orienting said
`indicium is of a character which would result in an
`appreciable reduction in the value of said diamond if
`diamond to situate said surface orthogonal to the axis of
`said indicium were removed.
`said beam;
`9. A me