Question 3: [1] However certain rocks, (such as lapis-lazuli) and organic materials (such as ________ or jet) are not minerals, but are still used for jewelry, and are therefore often considered to be gemstones as well.
Question 5: For example, diamonds, ruby, sapphires and ________ have been manufactured in labs to possess identical chemical and physical characteristics to the naturally occurring variety.
Question 7: The traditional classification in the West, which goes back to the ________, begins with a distinction between precious and semi-precious stones; similar distinctions are made in other cultures.
Question 9: The two main classifications are stones cut as smooth, dome shaped stones called cabochons, and stones which are cut with a ________ by polishing small flat windows called facets at regular intervals at exact angles.
Question 10: A gemstone or gem (also called a precious or semi-precious stone, or jewel) is a piece of attractive ________, which—when cut and polished—is used to make jewelry or other adornments.
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