What Is a Natural Red Clear Ruby?

Minerals

• A mineral is a naturally occurring, solid, inorganic substance with a crystal structure that can be obtained by mining. Inorganic simply means that the substance contains no carbon atoms. A crystal structure is an orderly spatial arrangement of atoms on a three dimensional lattice. There are many types of minerals.

Properties of a Ruby

• Ruby is a type of corundum, a crystalline mineral made of aluminum oxide with the chemical symbol Al2O3. Sapphire is also a type of corundum. Corundum is the second hardest mineral on the Mohs Scale of mineral hardness, with a score of nine, meaning that only diamond is harder than ruby. Hardness is a measure of scratch resistance of a mineral. Clarity is another property of a ruby. The higher the clarity, the clearer the ruby looks and the more valuable it is.

Impurities and Color

• What distinguishes ruby from other corundum minerals is the small amount of chromium impurities within the crystal structure of the ruby. The chromium, which makes up only around one percent of the mineral, replaces some aluminum atoms in the crystal lattice. Chromium absorbs yellow and green light, causing the ruby to appear red. Pure corundum is colorless. All other types of corundum are classed as sapphire and come in different colors, including blue, pink and yellow.

Differences Between Natural and Artificial Rubies

• Artificial corundum was first grown in a laboratory using a process known as flame fusion, but is now made using a process called flux growth. It can be difficult to tell natural and man made rubies apart, but there are a few tests you can do. For example, chemical analysis of a man made ruby may reveal trace amounts of impurities left over from the synthesis of the gem, such as lead. Another way to tell the difference is to look for characteristic curved growth features that only appear on lab-grown rubies.