This is so that the charge stays the same. When one in every hundred aluminum atoms is replaced by a chromium atom, it must donate three electrons like the oxygen atoms in order to become Cr3+ and replace Al3+. With pure corundum, there is no absorption of light, thus no color. This is the case for pure corundum when the electrons are paired differently and when atoms are replaced, the makeup of the crystal changes.Ĭlick Through for more information on Sapphiresģ.69 carat, Blue, Sapphire, Cushion Shape This allows for a crystal field to be created. This arrangement means that every two aluminum atoms give six electrons and every three oxygen atoms get six electrons altogether in order to produce Al2O3. At the same time, the surrounding negative oxygen atoms receive two electrons thus ensuring there are no unoccupied energy levels. The aluminum atom is a positive ion surrounded by six negative ions. This is how half of the aluminum atoms are arranged. The bottom atoms are set slightly further apart from one another than the atoms above. Though there are three oxygen atoms above the aluminum atom and three below, they are placed a little differently. The structure of this mineral consists of six oxygen atoms that surround every aluminum atom, creating a somewhat distorted octahedron. When in gem form, they are called colorless sapphires. Sapphires and Rubies - Lets Talk Science The Al2O3 CrystalĬrystals of pure Al2O3 are known as corundum. Let us take a closer look at these two gemstones and at what sets them apart from one another.Ĭlick through for more information on Rubies The color is what sets each of these stones apart, caused by the particular internal structure of the mineral. Red sapphires would exist too except they were given their very own category, rubies.

Pink, orange, yellow, green, and purple sapphires exist as well.

This mineral is found in an array of colors but is mostly known for its blue hue. Both rubies and sapphires are varieties of the mineral corundum. In fact, aside from their coloring, they are essentially the same stone.

The thing that most people find the most shocking about rubies and sapphires when learning about them for the first time is that they are both from the same mineral. Sapphires and Rubies - How Different Are They Really?

Ruby and blue sapphire together