What Are Fissures in Rubies?

Rubies are one of the hardest gemstones on the planet, reaching a 9 on the Mohr scale, just below diamonds. Rubies are made up mainly of the mineral corundum, but there are also traces of chrome, iron, titanium or vanadium, which gives the gemstone its color. It is rare to find a ruby that doesn't have fissures. Fissure-less rubies are extremely valuable.

Description

• A fissure is a crack or cleft in the surface of the ruby. Fissures are usually long and thin.

Appearance

• The opening to a fissure is usually small. The fissures can go from the opening on the surface into the ruby. The fissures inside of a ruby look like you punctured the gemstone several times with a pin. You can usually see this with the naked eye or with a jeweler's magnifying glass.

How Fissures Form

• Fissures form as the gemstones themselves form. Rubies are created deep within the Earth's core, where it is very hot. The rate that rubies cool from their molten, liquid state to their solid state determines the size and amount of fissures. If the rubies cool too quickly, more fissures will form. This happens if one part of the gemstone is a different temperature than another part. This temperature difference can cause stress on the structural integrity of the ruby, thus causing cracks and fissures.

Problems

• If a ruby has haziness or if the color is not as strong or desirable, sometimes the stone is heated to improve these conditions. During this process, sometimes a glassy substance gets into the fissures. These are then called glass-filled or fissure-filled rubies. Although the glassy substance makes the surface smoother and fills in cracks and pits, it also makes the ruby weaker in those areas. Rubies are normally one of the strongest stones you can get, but the glass-filled sites can break off much easier. Not only does it make it weaker, it also brings the monetary value down considerably.