Precious stones are valuable minerals or gemstones that are often used in jewelry and other decorative items. AGATE is a type of quartz that comes in a variety of colors and patterns. OPAL is a mineraloid composed of hydrated amorphous silica, which can display a range of colors. SAPPHIRE is a gemstone variety of the mineral corundum, which is typically blue but can also be found in other colors. GARNET is a group of silicate minerals that come in a variety of colors. RUBY is a pink to blood-red colored gemstone, a variety of the mineral corundum. GEM is a broad term for any precious or semi-precious stone. ZIRCON is a mineral that can come in a variety of colors, including yellow, red, brown, green, and blue. TOPAZ is a silicate mineral that comes in a variety of colors, including yellow, orange, pink, and blue. PEARL is an organic gemstone formed within the shells of certain mollusks. BERYL is a mineral composed of beryllium aluminum cyclosilicate, which can come in a variety of colors. JEWEL is a general term for any precious stone. EMERALD is a gemstone variety of the mineral BERYL, which is typically green. JASPER is an opaque, impure variety of quartz that comes in a variety of colors. DIAMOND is a transparent crystal of pure carbon, the hardest known natural substance. Ligure is a type of quartz that is usually gray or white in color.