Any gemstones that is not a diamond, ruby, emerald or sapphire is a semi-precious gemstone. Calling a gemstone semi-precious does not mean it is less valuable than precious gemstones. Semi-precious gemstones are just usually more abundant (but there are a few exceptions). The value given to semi-precious gemstones depend largely on color, availably and quality. Because these gemstones typically have more sources, they are a good choice for larger, clean-eye stones and come in a rainbow of colors. Some semi-precious gemstones are not stones at all, but are made of organic material like amber, coral and pearl. Some of the most popular semi-precious gemstones - garnet, peridot, amethyst, citrine, blue topaz and turquoise.