Star Sapphire Gemstone Phenomenon
Every gemstone, or any kind of product for that matter, always has that unique version, which is rare, more beautiful or special than its counterparts in some way or another, and valuable. When talking about sapphires, the ‘star sapphire’ fits into this category, as it is unusual and highly sought after. Sapphires are well known for their blue variety, though many other colors such as pink, yellow, and green sapphires exist as well. Those familiar with this term will know that the name ‘star’ refers to the star-like phenomenon that is present in some stones. It can also appear in rubies, which are known as ‘star rubies’.
The reason this phenomenon occurs in both gemstones is because for all intents and purposes, sapphires and rubies are the same gemstone. They are just different colors. To be fair, the fiery red color is a major differentiator and those stones that merely display a pale red or pink hue are known as pink sapphires and not rubies. The star shape is actually formed by intersecting needle inclusions. In general, inclusions are not something one wants in a stone, but in this case, these flaws work in the gem’s favor.
About the Inclusions
In order to understand the uniqueness of this stone, one must understand the complex nature of the inclusions that give it its distinct feature. A mineral called rutile, which is comprised of titanium dioxide, usually causes the inclusions. The needle-like inclusions form a star shape in a miraculous way.
Star Sapphire, Courtesy of By Mitchell Gore | Wikipedia
Twelve Ray Stars
Though six-ray star sapphires are rare enough, there is even a more unusual stone. This one displays a twelve-ray star. The phenomenon occurs when two types of inclusions are present in the stone: the rutile mineral and platelets of hematite. Rutile inclusions create a whitish star whereas hematite results in a golden star. The two stars become superimposed upon each other during the crystallization process, thus forming a twelve-ray star.
Largest Star Sapphires
Large sapphires are hard to come by, but large star sapphires are nearly impossible to find. That’s why the 1404.49-carat blue star sapphire is so famous. Called ‘The Star of Adam,’ the stone was mined in the south of Sri Lanka and is the largest blue star sapphire. The second largest is the Star of India, a 563.4-carat blue star sapphire, while the ‘Star of Bombay’ is yet another example of a large blue star sapphire. ‘Black Star of Queensland’ is the largest black star sapphire. At 733 carats it is the largest gem quality black star sapphire.
While sapphires are mainly assessed based on their color and weight, star sapphires are also graded according to the intensity, visibility, and color, of the asterism. If you are interested in such a stone, make certain to have this feature assessed carefully by a professional along with the other important elements of a sapphire.