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However, some other non-mineral rocks (such as lapis lazuli) or organic materials can also be also used for jewelry and are called gemstones. These include amber or jet. Pearls and coral are sometimes also called gemstones.
The Ancient Greeks began to decide which gems are precious and semi-precious. This continued in other cultures. In modern times, the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious.
Types of gemstones
- Bauer, Max (1968). Precious Stones: A Popular Account of Their Characters, Occurrence, and Applications, with an Introduction to Their Determination, for Mineralogists, Lapidaries, Jewellers, Etc. With an Appendix on Pearls and Coral. Dover Publications. p. 2. . https://books.google.com/?id=crc7ZtRHItgC&pg=PA1.
- "Book of Royal Gemstones" is a book from 1554 that talks about gemstones.
- "The Blossoms of Thoughts Regarding the Precious Stones" is an old book from the 1600s that is considered one of the most important books about precious stones. It is written in the Arabic language.