The blue sparkle of a sapphire and the red glow of a ruby are instantly recognizable. But there is a lot of confusion surrounding both stone types. In fact, their root mineral is the same one! So what makes the difference, and why are these stones considered so precious? That’s what we’re going to explore in this Spotlight a Stone article.
The History of These Colorful Stones
The name sapphire derives from the Latin word for blue, “sapphirus”, and rubies come from the Latin word for red, “ruber”. To understand these precious stones, you need to understand a mineral called corundum. Corundum is a crystalline form of aluminum oxide. In its pure state it is a colorless mineral, but with different impurities, it can take on a vast array of colors.
When corundum is mixed with chromium, the red color of a ruby comes out. This can be a light pink all the way into a deep red. In the U.S., a certain amount of redness needs to be present before a stone can be called a ruby. Corundum examples with only a little red are considered “pink sapphires”. This is a matter of debate.
Technically, all corundum stones that aren’t considered rubies can be considered sapphires. Corundum mixes well with a variety of impurities, resulting in colors all across the rainbow. There are even grey, black, and multicolored varieties. But the true sapphire is the blue variety, which is made when titanium and iron are in the right proportion inside the corundum crystal. Other colors are sometimes marketed as “fancy sapphires”.
Judging Rubies and Sapphires
Like diamonds, both rubies and sapphires can be judged on the 4 Cs, though color takes far more importance. The hue, saturation, and tone values of the color are all measured to help determine the ultimate value. Get more information on How to buy
But beyond the 4 Cs, there is another thing to consider with these stones. Rubies and sapphires were among the first stones to be made synthetically in a lab. The growth of corundum crystals is used in several industrial applications, such as making bullet-proof glass, due to their extreme hardness. It’s easy to introduce impurities into the process to create different colors.
Thus, a distinction can be made between synthetic and naturally-mined rubies and sapphires that can play a role in the price. A jeweler should have information on whether the stones in a piece were lab-created or natural. Synthetic stones aren’t necessarily worse than natural ones. Indeed, it’s much easier to create larger and more brilliant stones in the lab than it is in nature, but that’s why natural stones can be worth so much more.
Furthermore, nearly all sapphires and rubies are heat treated to bring out more clarity and color. In very rare circumstances, a sapphire or ruby might be gem-worthy without heating. There were several mines in Montana in the early 20th century that produced blue sapphires like this. These are known as Yogo sapphires.
But whether they are mined or artificial, heat treated or not, one thing is certain. Rubies and sapphires of any color are beautiful and worthy of use as jewelry. Their extremely high durability means that a purchase of these stones will create heirlooms that can last for generations. Stop by Grogan Jewelers today to examine our ruby and sapphire pieces.
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