If you have a color you like, there are various options to choose from.

Colors of Common Gemstones:

Clear:
Diamond, Moissanite, White Sapphire, White Spinel
White:
Moonstone, Opal, Pearl
Purple:
Amethyst, Iolite, Sapphire, Spinel, Tanzanite
Purple-Blue:
Iolite, Sapphire, Spinel, Tanzanite
Red-Purple:
Amethyst, Rhodolite Garnet, Ruby, Topaz, Rubellite Tourmaline, Alexandrite (incandescent light)
Red:
Ruby, Garnet, Spinel, Chrysoberyl, Topaz, Friedelite
Pink:
Pink Tourmaline, Kunzite, Rose Quartz, Spinel, Beryl, Pearl, Moissanite, Topaz, Sapphire
Peach:
Morganite, Garnet
Orange-Red:
Topaz, Citrine, Garnet, Sapphire, Friedelite
Orange:
Topaz, Citrine, Sapphire, Fire Opal, Spessartite Garnet, Spinel, Chalcedony, Sunstone, Zircon
Yellow-Orange:
Citrine, Amber, Topaz, Sapphire, Fire Opal, Chrysoberyl, Spinel, Zircon
Yellow:
Citrine, Diamond, Topaz, Lemon Quartz, Sapphire, Chrysoberyl, Spinel
Yellow-Green:
Peridot, Chrysoberyl, Tsavorite Garnet
Green:
Emerald, Tsavorite Garnet, Tourmaline, Sapphire, Jade, Malachite, Chrysoprase, Alexandrite (daylight)
Blue-Green:
Tourmaline, Topaz, Zircon, Sapphire
Blue:
Sapphire, Topaz, Aquamarine, Lapis, Turquoise, Zircon, Diamond, Spinel, Tourmaline
Brown:
Chrysoberyl, Spinel, Topaz, Garnet, Zircon, Tourmaline, Smokey Quartz, Tiger’s-Eye, Chalcedony
Black:
Onyx, Sapphire, Spinel, Smokey Quartz, Pearl
Multi Colored:
Agate, Alexandrite, Ametrine, Bloodstone, Chrysocolla, Jade, Jasper, Lapis, Opal, Rhodonite, Sunstone, Topaz, Tourmaline, Turquoise