Like the ruby, Sapphire Jewelry is a corundum type of gem, making it much harder and more enduring than other types of gems. Traditionally sapphire jewelry are best known for being a vivid crystalline blue in color, though what few people know is that sapphire jewelry can come in a variety of colors including green, yellow, and orange. The real definition behind this is that corundums will almost always be RUBIES if they're red and sapphire jewelry if they're any other color. Strange logic there, but that's how it's defined by a lot of gem collectors.
This stone can easily be likened to nephrite for two things: one, Turquoise Jewelry's considerably softer than other gemstones, making it easier to work with, and two, it is opaque. Turquoise Jewelry come in shades of sky blue with just a hint of green, and while it technically a stone the colors actually come from metals in the mineral - namely copper and iron traces. These metallic traces are the main reason for Turquoise Jewelry's opacity and malleability.
Topaz Jewelry is an aluminum silicate based gemstone and is primarily a rich yellow gold in color. Topaz Jewelry is semi transparent and is one of the harder and more enduring gemstones around. If the ruby "defines" red, the sapphire "defines" blue, and the emerald "defines" green for other gemstones, the topaz jewelry is the gemstone that sets the standards followed by other yellow colored gemstones.