Patented May 27, 1941 2,243,177

UNITED STATES PATENT OFFICE 2,243,177 COLORED Ludwig Weiss, Frankfort-on-the-Main, Germany, assignor to Chemical Marketing Company Inc., New York, N.Y., a corporation of New York No Drawing. Application May 1, 1940, Serial No. 332,841. In Germany April 13, 1939 5 Claims. (C. 5-165) My invention relates to the manufacture of a the contents of tin in the alloy between 1% and purple colored gold alloy containing thorium be 3%. Good results may also be obtained with low sides aluminum and gold. er additions of tin, for instance, 0.1 or 0.2 to 1%. It is known that gold combines with alumi An alloy of the following composition: num and forms an composition 5 of the formula, AuAl2 with a bluish or purple, Gold ------75 amethystlike color, containing 78.5 parts of gold Aluminum------24.25 and 21.5 parts of Al. This alloy, known as "ame Thorium ------0.25 thyst or blue gold' is not workable because of Tin ------0.5 its hardness, brittleness and its liability of break 0 has a beautiful bluish color, good workability and 3. may easily be hallmarked. Other gold alloys contain, besides gold and In carrying out my invention I may proceed as aluminum according to the formula AllAl2, addi follows: The composition Auale, i.e. 78.5 parts of tional quantities of aluminum or other soft gold and 21.5 parts of aluminum, may serve as such as , tin, , , bismuth, thal 5 starting material, whereby one or both of these lium either alone or in combination in quanti metals are partly substituted by thorium Or ties which facilitate the workability of the alloy thorium and tin. without a harmful influence to the color effect. It has proved advantageous to substitute one The total amount of these additional soft metals part of the aluminum by thorium or thorium and should not exceed 40% of the alloy. With these 20 tin respectively. This makes it possible to obtain additions of Soft metals gold alloys of various beautiful workable alloys with a high content of shades are obtained, for instance, from red over gold, for instance, 75% gold, corresponding to a a purple shade to a violet color, i. e. especially hallmark of 18 karat. colored red alloys which are Workable The alloys, according to my invention, may als and suitable for the manufacture of jewels. contain, besides the main constituents gold, alu Now it was found that the qualities of the gold minum and thorium or thorium and tin, small aluminum alloys, especially those of the formula quantities of other metals such as silver, zinc, AuAl2 may be considerably improved with respect cadmium and the like. to the workability by adding thorium in suitable Other components of the alloy may be iron, amountS. 30 , , , . The addition These new alloys according to my invention of Small quantities of these metals either alone may, for instance, also contain thorium in quan or in combination may influence the qualities of tities up to about 10%, besides gold and alumi the alloys with respect to and the like num. If a beautiful blue Color is desired, the con and also in regard to the color Shade. Of course, tents of thorium in the alloy must be kept below the quantity of these additional metals is pro 7%. It is also possible to add very small amounts portioned in such manner that harmful in of thorium, for instance, such which do not ex fluences may not occur. Generally, it was found ceed 1% of the whole alloy. Gold aluminum al advantageous to keep the amount of these loys with a thorium content of, for instance, 0.5% lic additions, alone or combined with each other, to 1% have a beautiful shade, good workability 40 below 5% preferably below 2% of the total alloy. and ductility. The thorium content may even As the alloys are susceptible against , I be kept lower, especially if other metals with im prefer to work airsealed. For instance, I may proving qualities are present. The lower limit of proceed in such manner that at first the alumi the content of thorium is, for instance, about num is molten under a salt layer whereupon the 0.5% of the total alloy. 45 other ingredients are added in the following or Furthermore, I have found that the ductility der: tin, gold, thorium. of the alloys may be increased by adding tin in The alloys may be used for various purposes. quantities of about 7% besides gold, aluminum They are especially suited for the manufacture of and thorium. jewels. Generally, it has proved advantageous to keep 50 What I claim is:

2 2,243,177 1. A workable gold alloy having a purple co 4. A workable gold alloy having a purple col ored shade consisting of 75 parts of gold, 10 parts ored shade consisting of from about 75.5% to of thorium, 15 parts of aluminum. 78.5% of gold, from about 18.5% to about 21.5% 2. A workable gold alloy having a purple col of aluminum, and about 3% of thorium. ored shade consisting of from about 68.5% to 5. A workable gold alloy having a purple col about 8.5% gold, from about 11.5% to about ored shade consisting of from about 68.5% to 21.5% aluminum, and from about 0.5% to 0% about 8.5% gold, from about 0.5% to about 10% thorium. thorium, and the remainder substantially all 3. A workable gold alloy having a purple col aluminum, the aluminum constituting not over ored shade consisting of from about 71.5% to 10 24.25% of the alloy. about 78.5% of gold, from about 4.5% to about LUDWIG weiss. 21.5% of aluminum, and from about 0.5% to about 7% of thorium,