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INVENTION
Patent of the Russian Federation RU2215455
METHOD OF PAINTING NATURAL AND SYNTHETIC JEWELRY STONES
Applicant Name: Institute of Experimental Mineralogy, RAS
The name of the inventor: Balitsky VS; Balitskaya L.V.
The name of the patent holder: Institute of Experimental Mineralogy, RAS
Address for correspondence: 142432, Moscow Region, Noginsk District, Chernogolovka, IEM RAS
Date of commencement of the patent: 2002.06.18
It is intended for use in the jewelry industry when painting colorless and pale blue sapphires, colorless topaz, quartz. The method involves placing the jewelery stones in a finely divided powder of cobalt oxide with a ratio of the oxide and oxide forms of cobalt 1: 1 mixed with zinc oxide in the ratio of cobalt oxide to zinc oxide as 1 
0.25-3) and subsequent heat treatment in an oxidizing atmosphere at 900-1250 ° C. It is possible to obtain stable stains of natural and synthetic jewelry stones in a wide range of colors.
DESCRIPTION OF THE INVENTION
The invention relates to methods for processing natural and synthetic jewelery stones, in particular methods for staining sapphires from colorless and pale blue to bright blue, from pinkish-violet to cornflower blue, from changing green in daylight to pinkish-red in electric Light to, respectively, bluish-green in daylight against blue in electric light; Colorless topaz - in colors from blue to greenish-blue and bright green; Quartz - in an unusual blue color, and can find application in the jewelry industry.
A method for coloring colorless leucosapphire crystals in blue is known, according to which cobalt is deposited on the crystal surface by sputtering in a metallic form and a solid-phase chemical reaction of the crystal material with a metal deposited on its surface is carried out by thermal treatment in air at a temperature of 1100 ° C for 30 minutes. Certificate of the USSR 768455, class A 44 dated 17/00, published on 07.10.80 ).
The disadvantage of this method is its limitedness in relation to the possibility of staining other jewelry stones. In particular, this refers to topaz and quartz. Topaz does not interact with the metallic cobalt deposited on its surface to a temperature of 960 o C, but at a higher temperature it begins to break down due to the transition to another mineral phase, mullite. Quartz is also not colored by metallic cobalt deposited on its surface at the heat treatment temperature specified in the analogue.
There is a known method for staining natural and synthetic jewelry stones, in particular topaz - in bluish-green color and quartz - in pink color, according to which polished jewelry stones are placed in a finely ground powder of cobalt or cobalt oxide and followed by heat treatment in an air atmosphere at 900- 1250 ° C for 3-200 hours ( US Pat. No. 5,888,918, class C 30 V 029/00, A 44 C 17/00, published on 30.03.99 ).
However, stones stained with this method have a limited spectrum of colors.
The proposed invention solves the problem of developing a dyeing technology for a large class of natural and synthetic gemstones, the technical result of which is the production of stable stains in a wide range of colors.
The technical result is achieved by the fact that in the method for staining natural and synthetic jewelry stones including placing them in a finely divided powder of cobalt oxide and subsequent heat treatment in an oxidizing atmosphere at temperatures of 900-1250 ° C., according to the invention, an oxide with a ratio of the oxide and oxide Forms of cobalt 1: 1 and added to it a finely divided powder of zinc oxide in the ratio of cobalt oxide to zinc oxide as 1 0.25-3).
At other ratios of ferrous and cobalt oxide in cobalt oxide, sapphires, topaz and quartz do not stain. If the ratio of cobalt oxide to zinc oxide is less than 1 to 0.25, the color is not visually distinct compared to the staining only in cobalt oxide. The ratio of these oxides more than 1 to 3 leads to the poisoning of the surface of the stones, the adherence of the newly formed mineral phase to it.
When processing sapphires, the best results for their coloration are obtained with a ratio of cobalt and zinc oxides 1: 2 and the duration of heat treatment for 2 hours at 1100 ° C.
When staining topaz, the optimum ratio of these oxides of cobalt and zinc is 1: 2 and the duration of heat treatment for 5 hours at 950 o C.
When staining quartz, the optimum ratio of cobalt and zinc oxides is 1: 3 and the duration of heat treatment for 10 hours at 900 o C.
The positive role of the additive in the reaction mixture of zinc oxide is to form a more intense and clear color.
A variety of colors is achieved by using not only colorless but also primitively colored stones with unpopular or pale coloring as a starting material due to mixing of their primary color with the newly formed color of the stone surface.
Example 1
A jeweler's inset of pale pink sapphire is placed in an alundum crucible with a mixture of finely ground cobalt oxide with a ratio of the oxide and oxide forms of cobalt 1: 1 and zinc oxide. The ratio of cobalt oxide to zinc oxide is 1: 1. The crucible is placed in an electric furnace, heated at a rate of 3 ° C./min to a temperature of 1100 ° C. in an air atmosphere, maintained at this temperature for 2 hours and cooled at a rate of 5 ° C./min. As a result, the stone is painted in the most popular for sapphires cornflower blue color.
Example 2
The same as in Example 1, but the cobalt oxide powder contains only its ferrous (Co + 2 ) form. After the end of the process, the stone did not change the original color.
Example 3
The same as in Example 1, but the cobalt oxide powder contains only its oxide (Co +3 ) form. After the end of the process, the stone did not change the original color.
Example 4
The same as in Example 1, but the ratio of cobalt oxide to zinc oxide is 1: 0.20. As a result, the stone is painted in a very pale blue color, unsuitable for use in jewelry.
Example 5
The same as in Example 1, but the ratio of cobalt oxide to zinc oxide is 1: 3.2. As a result, the stone is covered with an opaque film of dark blue color, loses its polishing and becomes unusable in jewelry.
Example 6
The same as in Example 1, but as a starting material, a vanadium-containing sapphire with a variable color is used: green in daylight and pinkish red in electric light. As a result, a stone is obtained with a changing color, but other colors: bluish-green in daylight and bright blue in electric light.
Example 7
A jeweled polished insert made of colorless topaz is placed in an alundum crucible filled with a mixture of cobalt and zinc oxides in the ratio 1: 2 (the ratio of the ferrous and oxide forms of cobalt and is equal to 1: 1). The crucible is placed in an electric furnace, heated at a rate of 1 ° C./min to 950 ° C., kept at this temperature for 5 hours and then cooled at a rate of 2 ° C./min. As a result, the insert is painted in a greenish-blue color, close to the color of the topaz from the Volyn deposit.
Example 8
The same as Example 7, but the ratio of cobalt and zinc oxides in the powder mixture is 1: 4. As a result, the insert is painted in an intense blue color, patchy and opaque, and becomes unusable in jewelry.
Example 9
The same as Example 7, but the ratio of cobalt and zinc oxides in the powder mixture is 1: 0.20. As a result, the insert is painted in a dirty-bluish-green color, not suitable for use in jewelry.
Example 10
A jeweled polished insert made of colorless quartz is placed in a crucible with a mixture of cobalt oxides with a 1: 1 ratio of cobalt oxide and cobalt oxide in a ratio of 1: 3, placed in an electric furnace, heated at a speed of 0.5 o C / min to 900 C., kept at this temperature for 10 hours, then cooled at a rate of 1 ° C./min. As a result, the insert is colored in an intense blue color, close to the color of the blue synthetic quartz.
Example 11
The same as Example 10, but the process is carried out at a ratio of cobalt and zinc oxides as 1: 0.25. As a result, the insert gets a barely noticeable pink tinge.
Example 12
The same as Example 10, but the process is carried out at a ratio of cobalt and zinc oxides as 1: 3.2. As a result, the insert is covered with an opaque blue layer and has no jewelry value.
As can be seen from the examples given, carrying out the staining process within the declared limits makes it possible to obtain a stable coloration of the main classes of natural and synthetic jewelery stones in a wide range of colors.
CLAIM
1. A method for staining natural and synthetic jewelry stones, comprising placing them in a finely divided powder of cobalt oxide and subsequent heat treatment in an oxidizing atmosphere at 900-1250 ° C, characterized in that as an oxide of cobalt, an oxide with a ratio of the oxide and oxide forms of cobalt 1 : 1 and add finely powdered zinc oxide powder in the ratio of cobalt oxide to zinc oxide as 1: (0.25-3).
2. The method of claim 1, wherein the sapphire staining is carried out at a ratio of cobalt and zinc oxides of 1: 2 and a heat treatment time of 2 hours at 1100 ° C.
3. A process according to claim 1, characterized in that the topaz staining is carried out at a ratio of cobalt and zinc oxides of 1: 2 and a heat treatment time of 5 hours at 950 ° C.
4. The method of claim 1, wherein the staining of the quartz is carried out at a ratio of cobalt and zinc oxides of 1: 3 and the duration of the heat treatment for 10 hours at 900 ° C.
print version
Date of publication 09.12.2006гг
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