Apart from the minerals already described, there are a few other substances which are commonly used in jewelry. Like pearl, they should not be strictly included in this work, but to ignore them would be an omission which the reader would not expect. During the course of his business, the jeweler will have handled all the materials which we are about to describe, and the public will have seen various articles of jewelry or utility made from them.
Amber, coral, and ivory have not the commercial value of most gem stones, but they have been used as a medium of expression by many artists of renown. They have a long history and take a place in the civilized works of many peoples. All these products of nature about to be discussed are of organic origin, a product of something which has once lived, and therefore they are not minerals, or stones.