Onyx is a banded stone not unlike agate. It was formed from limestone so it is a soft stone. Color variation comes from dissolving and redepositing of the limestone. Colors of this strikingly luminescent stone vary from white to black and every color in between. The appearance and color of onyx change with the variations in light. This makes it an exciting building material.

Onyx floor tiles grace bathrooms, kitchens, and foyers adding an air of opulence to your home. Because of their extreme color variations, onyx can be used to create a focal point such as a bar or fireplace.

Onyx as a choice for building stones must be made carefully. While its color variation is much like marble, this substance is not nearly as hard as marble. Thus it must be handled and cut with care.

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. This guide will reveal details about some of the most popular semi-precious gemstones - garnet, peridot, amethyst, citrine, blue topaz and turquoise. For information on the only semi-precious gemstone that comes from an organism, take a look at the pearl buying guide.