Mrs. Sippi’s SmarterScience site

Bombay sapphires: Do they exist? That's geology!

Bombay Sapphire gin is a Bacardi brand and the name has something to do with the popularity of gin in the British empire in India.

The name sounds fairytale-like to me and hints at a certain richness, conjures up images of treasure troves filled with oriental jewelry and an Aladdin's lamp or two all placed on marvelous oriental carpets with deep burgundy colors and a hint of purple here and there.

It also raises a question or two. What exactly are sapphires and do Bombay sapphires exist? And what is Bombay Sapphire gin? I decided to investigate.

So I went online to search for the gin and I also asked my boss to buy some of the stuff for me. By then it was almost Christmas, and the gin was therefore sold in a nice tin with holographs of the Bombay Sapphire gin bottle and of a festive glass.

The first thing I found online was that this gin gets its flavor and fragrance from ten ingredients: almond, lemon peel, liquorice, juniper berries, orris root, angelica, coriander, cassia, cubeb, and grains of paradise.

The liquid is distilled three times, and the alcohol vapors are passed through these ingredients. Then, so the story according to Wikipedia goes, water from Lake Vyrnwy in Wales is added.

The bottle is the color of blue sapphire and carries the image of Queen Victoria of the British Empire.

It sounds irrestibly entrancing! Grains of paradise, even! Who wouldn't want those? I took my gin glass out of the cupboard right away.

But what about those other grains of paradise? Sapphires! What are they, sapphires. Can you find them in Bombay, nowadays called Mumbai?

Sapphires are gems that belong to the corundum family. Corundum is a very hard mineral; its hardness is 9 on the Mohs scale which runs to 10. That means that only diamonds are harder and can scratch sapphires (or any other mineral variety). Corundum consists of aluminum and oxygen: Al₂O₃. (Yes, you could joke that it is merely rust, not of iron, but of aluminum.)

Sapphires are yellow or blue corundum. Blue corundum contains some iron (Fe) and titanium (Ti); red corundum (ruby) contains chromium (Cr). Yellow corundum contains trivalent iron (Fe³⁺) and green corundum divalent iron (Fe²⁺).

So-called star sapphires contain needles of rutile which is a titanium mineral. (For comparison: There are also quartz varieties that contain rutile needles, which can be clearly visible as black or honey-colored needles; you sometimes see this quartz variety at mineral shows, such as in this picture, as hangers.)

According to the Bacardi web site, the inspiration for the gin's name was the 60-carat "Star of Bombay" sapphire which was discovered in Sri Lanka and is now in the Smithsonian Institute.

Corundum as a gem can be more valuable than diamond. As corundum is very hard, low-quality corundum is also used as or in an abrasive: emery.

Corundum is mainly found in certain igneous rocks, such as syenites and related pegmatites (picture is of a pegmatite with black tourmaline crystals, from southern France) and in some (aluminum-rich pelitic = derived from clays, and clays tend to contain a lot of aluminum) metamorphic rocks. Igneous rocks are solidified molten rocks. Metamorphic rocks are rocks altered by, mainly, a combination of pressure and temperature. There are online courses you can check out, if you want to know more about igneous rocks or metamorphic rocks.

That still does not tell me whether sapphires are found in or at least near Mumbai (Bombay)! Yes, sapphires are found in India, but India is a very large country.

As it turns out, Mumbai has a unique geology (link goes to pdf file of a scientific publication) that makes it very unlikely that sapphires will ever be found there.

Mumbai is located on the so-called Deccan Traps, a large basalt area. Basalts are lavas. These are also igneous rocks but with a very different chemistry than syenites and certain associated pegmatites in which corundum can be found. Chemically speaking, basalt is almost on the complete other end of the chemical range of rocks!

If you were to compare it to colors, basalts would be very dark grey, almost black, whereas syenites and pegmatites would be white, with all the other colors in between! (Funnily enough, in reality these colors tend to work out that way too for these rock types.)

Or, put another way, finding sapphires in basalt would be as uncommon as finding tropical fish growing on a tree in the woods of England or the forests of Norway.

So, no, the only places in Mumbai where you can find sapphires are likely to be jewellery shops. Don't tell me you were already planning your next vacation there to search for sapphires!!! It ain't that easy! But they sure are pretty, blue sapphires. As pretty as the blue bottles of Bombay Sapphire gin.

(See the elegant high-stemmed glass on the right side of the tin and the bottle on the left side of the tin with the holographs in the picture on the right?)

(Note: The so-called Bombay High is an off-shore oil field.)