by Watchking

Since the color of gold has become part of the consumer psychology gold has been used as a covering on other materials to decoratively enhance them and to reduce allergic reactions.  There have been three basic ways that a gold surface has been applied to a base metal watch case:

Gold filling is the most durable because a base metal sheet is etched and then two sheets of some karat gold are placed on either side of the base metal sheet. Under great pressure the three sheets of metal are pressed flat and in most cases the karat gold can represent about 15-25% of the total mass of this three-layer metal. 

Rolled gold plate  is similar except that the sheets of base metal are thicker proportionally. In these first two cases the multi-metal material is made first and then the "blanks" are formed into the desired case shape afterwards. 

Gold electroplating involves making a case out of a base metal first and then etching the case so that it will accept an even layer of karat gold (the "gold" layer's thickness is usually measured in microns). "Resist" can be applied to those portions of the case where gold plating is not desirable. If 18 - 24 karat gold plate is to be applied there is sometimes an intermediary step of "electro-blasting" tiny copper nodules onto the base metal before the plating process is undertaken. This will help the softer gold platings to adhere to the case material.

When a watch case has only a thin layer of gold alloy on it's surface the rule is "the harder the better". Gold is very soft, even 9 karat green gold (which is one of THE hardest gold alloys) is much softer than steel and many other kinds of base metal. This means that the gold alloy on the surface of the case will wear off fairly easily. This also means that a heavy 10 karat gold plating or filling on a watch may last substantially longer than an 18 karat plating or filling. The reality is that the amount of actual gold in watch case with a plated or filled surface is so insignificant that the real value in the gold finish, involves how long it will last and look attractive. In this case the reverse of normal buying psychology should be employed. The lower gold content in 9 or 10 karat gold makes them better for plated or filled cases because they will stand up to daily use without wearing through quickly.

Unfortunately the high percentage content of other metals in 9 or 10 karat gold may trigger allergic responses in some people. Pitting is also a possibility not only in gold-filled or plated surfaces but also even with solid 9, 10, 12 or 14 karat gold. Certain acids produced by the body or found in industry will actually attack the base metals in gold alloys. If the gold plating is very thin (less than 10 microns) it is possible for oxidation to come through the gold surface material. Gold is dense but can be porous.

The psychological desirability of gold finishes goes back in human interest for thousands of years. The gold tomb ornaments of the early Egyptians still enthrall tourists who see them. Even though 18 karat white gold is costlier and contains more precious metal than 18 karat yellow gold, the yellow versions are definitely more popular. Gold finishes and solid karat gold cases give watch buyers a "feeling" of luxury. If buyers are aware of the realities of gold and gold alloys, it will be possible to make a better decision about buying watches with gold finishes.

The actual amount of gold in most watches is only a small portion of their retail value. A watch with 3 ounces of 18 karat gold used in its manufacture will likely retail for more than $5,000, while the value of the gold will be less than $750. This same watch made of all stainless steel, will likely cost 40%. This shows us the fascination humans have with gold. The old adage is that "gold doesn't lose its lustre", both a fact of science and a comment on the psychology of gold.