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Learning Library

Indian Star Ruby Gemstone

Whenever we throw open the doors to a request show here at Gemporia, almost without fail somebody will be asking for a Star Ruby. It has been YEARS since we were able to fulfill one of these requests and it’s for this reason we are so delighted to announce this extremely limited new collection of Indian Star Rubies.

Demand for Star Ruby is always so high, and coming from so many different people, that we wanted to make this collection available to as many of our customers as our tiny supply will allow. This is why, with the exception of one pendant in gold, we’ve set this entire find in sterling silver.

These remarkable Indian Star Rubies come from a new Corundum (the parent family of Ruby and Sapphire) discovery in Tamil Nadhu province in India. They are classed as very unusual, as the Ruby is forming or has formed on top of grey-blue Sapphire, which has caused the deep cherry-to-purple Ruby colour in the body of this new Star Ruby find.

The Tamil Nadhu province is found at the very southern point of India on the eastern side, facing towards Sri Lanka. This is one of the most famous areas of the world for Ruby and Sapphire, and it’s not hard to see why just across the water from the island that gave us Ceylon Sapphire, we’ve found this remarkable deposit of Star Ruby.

It is important to remember, especially if you’re indoors when you first glimpse this beauty, that no Star gem will look good in blanket lighting with multiple light sources. You just will not get a good star if the cabochon is flooded with light. This is normal, and applies to all star gems. Get the piece out into bright sunshine and the star comes alive. A single light source is what brings the star to the front, and in the studio I’d recommend bringing the studio lights down 

and using a bright torch or the light on a smartphone to imitate the sun. Try this out for yourselves first so you get used to showing it – I held the ring under a desk to block the office lights and used the light on my phone and got a great star out of a couple of these new designs.

Many years ago I saw a ‘created’ Star Ruby that was real Corundum but had been grown in a lab at an accelerated pace. As beautiful as it was, this natural Star Ruby, in a bright single source light, wins hands down.

The definition of Chatoyancy (Cat’s Eye) and Asterism (Star Gems) comes down to whether there is a presence inside the gem of a single band of light (Chatoyancy) or a number of intersecting light bands (Asterism). This undoubtedly gives the gem a magical, mystical even ethereal quality, immediately elevating it above its peers in both rarity and desirability. Be careful how you use this on air, but obviously this also has an effect on the value of the gem too. Always encourage people to “get it valued/appraised!”

As mentioned above, it’s a known characteristic of the gem that multiple light sources will lessen the effect of the cat’s eye or star. Single light sources are the best way to enjoy this natural phenomenon, most preferably the sun. It’s not uncommon for the effect to disappear altogether in ill-defined light sources so don’t worry if you think you’re star isn’t there.

The science! Corundum commonly forms in clay rich limestone, specifically during the metamorphism stage of the rock (when the rock is changing, basically). As these Corundum crystals (which are pure aluminium oxide) grow, they begin to incorporate titanium atoms. As the crystal cools, these titanium atoms bond with oxygen atoms and form minute needle like rutile crystals (now titanium oxide) within the future gemstone. These rutile crystals are forced to align with each other by the growth of the corundum, so they form sets of parallel crystals.

In Ruby and Sapphire, these parallel bands of rutile inclusions orient themselves as three bands, lying horizontally at 120 degrees from each other, so when viewed from directly above they intersect with each other as a perfect star. For this to work the rutile inclusions must form along the growth axis of the crystal. It is down to the skill of the lapidarist to correctly identify this star and its orientation within the rough gem BEFORE making the first cut – otherwise nature’s miracle goes entirely to waste. As with many gems, the human element shouldn’t be under-appreciated. The gem must then be cut as a cabochon to bring out the star – any other cut and it simply won’t show its hidden star. On top of this, the peak of the dome of the cabochon must coincide with the centre point of the intersecting inclusions or the star will be lopsided and in many cases may not even show at all.

Whist this method of formation applies specifically to Corundum (Ruby and Sapphire), similar phenomena can occur in other minerals too. Quartz for example is famous for showing the Tiger’s Eye (Chatoyancy) effect. Quartz can also produce 6- and 12-rayed stars, the latter notable by their extreme rarity. Garnet can give us 4-, 6- or 8-rayed stars and I’m personally not aware of a single Star Garnet coming through Gemporia Towers at any point in the last 10 years. Spinel can show 4- and 6-rayed stars, but ditto the above. In very rare finds, Kornerupine can display a 4-rayed star. The elements and formation may vary from gem to gem but the inclusions will always be tiny, reflective hollow tubes or fibrous crystals that vividly bounce back single light source.

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