For the first 900 years coins were monochrome -- one color! -- the color of bronze, silver, or gold. It was Max Schwab who began selling equipment to mints and jewelers in 1550 that allowed jewelers to strike their creations. They could have a pin, say, struck in metal with Maxz Schwab's equipment and then add color. But this didn't happen to coins or medals.

It was jewelers who applied an ancient technique of melting colored glass to give color to their metal jewelry. They learned they could break the glass into tiny pieces, lay this in a cavity in a metal item and fire it -- place it in an oven whose temperature would melt the glass but would not melt the metal. [Glass melts 750 to 850 degree Centigrade; copper, for example, melts at 1085 degrees C).

In time, Jewelers applied this technique to decorations and the elaborate regalia worn by royalty. Really good jewelers became Royal Jewelers and these are the ones who made decorations in elaborate design, with skilled techniques, and color in the pendant medals, ribbons and sashes.

Their technique in making decorations and orders in color was preparing glass in solid pure colors by grinding to a power form. The metal base had either a cavity or a fence -- called a casson -- in which they poured the powdered glass. When fired the glass melted, flowed and solidified within the confine of that intended area. This was the process of enameling.

Enamel provided vibrant colors, a smooth, hard surface (but it could chip), and last as long as the metal base. It was ideal for decorations but it was not ideal for coinage. Thus coins remained monochrome for so many centuries.

The first attempts to color a coin was a plug of a different colored medal. This followed, only recently, by ring technology of blanks of two, then three rings of contrasting color.

The end of the 20th century brought an explosion of colorizing coins and medals. Let me count the ways:

1) Contrasting metal in the blank (plug or ring).

2) Plating -- a coin or medal is masked off for the area NOT to be plated before it is inserted in a an plating tank for deposition of a contrasting color metal; the masking material is removed afterwards to exhibit the two metal surfaces.

3) Organic coating -- paint -- unsatisfactory because paint on coins and medal easily chips off, becoming unsightly. (But a medal was so treated in the 20th century, the Fairmount Park Art Association Medal of 1937 in Philadelphia was painted black.)

4) Enamel -- and there are several kinds of enamel.-- hard and soft, both with and without those fences mentioned above. They have a lot of French names: Cloisonné (that has the fences or wires to form a cell), champlevé (like Limoges enamel), grisaille (a type of painted on enamel), plique-a-jour (a transparent or translucent enamel), and others.

5) Embedments -- an item in contrasting color is embedded on the surface of a coin or medal, holograms fit in this category.

6) Pad printing -- a somewhat new technology of "printing" one or more colors on the modulated surface of a coin or medal. The ink is applied to a pad which imparts that ink to the metal surface.

7) Stickers -- Paper stickers printed in color are pasted on to a coin or medal -- "Elvis Presley coins" are made by this process.

This discussion was brought to mind by the Holstein-Cow Medal by Gozo Kawamura illustrated in last week's E-Sylum. Despite the fact this medal was made by Medallic Art Company and I cataloged it for the company while I was first employed by the firm, I cannot say for certain how the colors were applied.

It is NOT cloisonné enamel. Particularly because it does not have the fences and is enameled on both sides. If you fired a second side the enamel on the first side would melt and flow off. Such a technology, however, has been developed. It is called "Counter enameling" and it has been practiced with great skill by the Paris Mint which has issued two-sided cloisonné medals.

On the cow medal it could possibly be the white or silver color is some form of plique-a-jour and the black a grisaille. I have defined and written 1,840 technical terms in the coin and medal field for an Encyclopedia of such numismatic terms. I have 12 yet to write. Enamel and Enameling is one of those.

To read the earlier E-Sylum article, see:GOZO KAWAMURA, COW MEDALLIST(www.coinbooks.org/esylum_v15n04a16.html)