Final answer:
The most commonly faceted opals are called precious opals, which exhibit a play of colors or iridescence when viewed from different angles. These opals are usually found in Australia, particularly in the states of New South Wales and Queensland. Faceting opals requires skill and expertise due to their delicate nature and potential for fracture.
Step-by-step explanation:
Opals are gemstones that are commonly faceted for use in jewelry. However, not all opals are suitable for faceting. The most commonly faceted opals are called precious opals, which exhibit a play of colors or iridescence when viewed from different angles. Precious opals with a vibrant play of colors are highly valued and are often used in faceted gemstone designs. These opals are usually found in Australia, particularly in the states of New South Wales and Queensland. They have a unique structure that allows light to diffract and create the characteristic play of colors. Opals from other locations, such as Mexico and Ethiopia, are also sometimes faceted, but Australian opals are the most well-known and sought after. Faceting opals requires skill and expertise due to their delicate nature and potential for fracture. Faceters carefully cut and shape the opal to maximize its color play and beauty. The faceted opals can be used in various jewelry designs, including rings, pendants, and earrings, adding a touch of elegance and uniqueness to the wearer's style.