Despite the commercial value of natural-color diamonds, distinguishing them from treated diamonds remains a significant identification challenge. While some diagnostic visual features exist ...

The 1980s have seen an explosion of interest in the cultured black pearls of French Polynesia, five groups of island archipelagos in the South Pacific. Twenty years ago, black pearls were a mere ...

Malaya garnets from Bekily, Madagascar, are predominantly pink to pinkish orange, with some stones orange to red. Discovered only in the late 1990s, the majority are intermediate members of the pyrope ...

Jewelry-quality synthetic malachite is now being manufactured in the USSR. The texture, structure, and physical and physico-chemical properties of this synthetic malachite are reported. Three textural ...

Although lost for literally hundreds of years after the Spanish conquest of the Aztecs, many deposits of jadeite have been found in Guatemala during the last two decades. Following the discovery of ...