Amethyst is an extremely sought-after gem which has been valued by many civilizations since antiquity. A variety of vitreous quartz, amethyst often forms dramatic prismatic crystals which are often formed into jewelry without being cut. Brazil and Uruguay are common sources of high quality amethyst. In the early Christian church, amethyst was believed to guard against intoxication, hence its derivation from the Greek "amethustos," meaning "not drunk."

Natural pearls are formed when an foreign object becomes trapped in the shell of an oyster or pearl and the animal surrounds the object with several mineral layers in order to protect its soft tissue. Most pearls sold today are farmed pearls, created by intentionally inserting small mother-of-pearl beads in the oyster's shell. The resulting pearls are harvested up to two years later. Pearls come in a range of pastel colors from cream to blue to pink, and irregularly shaped pearls are often called "baroque" pearls. Mabe pearls are hemispherical cultured pearls grown against the inside shell of an oyster rather than in the mollusk's body. Mabe pearls are typically used in settings such as that conceal their flat backs.

Shells are mineral structures formed by aquatic creatures and land mollusks. Lustrous shells including mother-of-pearl have been carved into cameos and buttons since antiquity. The beauty and variety of shells make them a sought-after decorative material.

Tourmaline is a coveted stone that comes in a wide range of colors from black to pink, green and blue. Crystals which display more than one color together are common. A cross-section of a watermelon tourmaline crystal reveals green on the outside and pink within.