Discover the science of gems with Tanja Sadow

Guest Author – Dominic Fondé is a freelance artist living and working in Singapore. He specialises in glass engraving, creating artworks for private clients and gallery sale. He also teaches regular classes in glass art. To find out more about Domonic and his artwork, please email him at

Tanja Sadow

As part of the ongoing Science in the Café series at Science Centre Singapore, Tanja Sadow, dean and founder of the Jewellery Design and Management International School will present a talk on 14 December titled ‘Discover the Science of Gems’.

As I sit down to discuss gemmology with her, she almost immediately corrects my inaccurate research that there are 3,500 known types of mineral, nonchalantly noting that the number is now over 4,000 since every year, 30-80 new minerals are discovered! I phrase my question as ‘So there are over 4,000 or so known types of minerals but only some qualify as a gem, what are the criteria?”

The answer it would seem is a combination of things, chemical composition, crystalline form, durability, rarity and, not surprisingly, beauty. “Of course not all gems have the same value”, she explains. “The best value gems are measured on their tone, hue, saturation, clarity and cut as well as their overall weight. Ever wondered what the most expensive gem in the world is?”

Before I have the chance to guess, she enthusiastically follows up with “True or false? If you rub a pearl against your tooth can you tell if it is an imitation or cultured pearl?”

I have no idea if this is true or not but before I can really consider this she throws another riddle at me. “Did you know that rubies actually have the same chemical composition and crystal structure as sapphires? They are one of only two stones in the corundum family that are so rare and valuable that they have their own special name.”

Again, I did not know this. By now it is becoming clear that Tanja not only knows her subject inside out but that she knows how to work an audience, dropping interesting crumbs of information that get the listener hooked. Her knowledge spans not only the practical methods of grading and identifying gemstones but also the field of history.

“Did you know that synthetic ruby was the first laboratory-created gemstone and we have been making these since the 17th century?”
Synthetic ruby? Now this sounds like it could be a plot element from a James Bond film. “Why would anyone want to create a synthetic ruby?” I ask, hoping the answer has something to do with taking over the world. The answer it turns out is not quite as dramatic as that but fascinating all the same.

“Imitation gems have been created as an alternative to the natural gemstones because gems also have important uses in industry as abrasives, gain media for lasers, and even low friction bearings, but synthetics also provide more affordable alternatives for those that want to wear gem stones on a budget”, she tells me.

“These days they are so convincing that you would need an extremely well equipped laboratory to be able to tell a natural ruby from a synthetic one. Diamond is the hardest substance known to man but it is not the toughest, what is?”

By now I know she does not expect me to know the answer. She is gently teasing me, hinting that I will have to turn up to her talk on Friday in order to get the answers.  Well, fair enough, she has me more than intrigued me! I’ll be there taking notes, and having my curiosity satisfied when I match answers to her questions.

Be sure to attend Tanja’s talk – ‘Discover the Science of Gems‘ on 14 December, starting 7 pm at the Newton Room in Science Centre. Kindly note that pre-registration is required and that admission charges apply for non-members of Science Centre Singapore.

Tanja Sadow is a qualified Gemmologist with the Gemmological Institute of America and an educator in this field for 30 years, so she is well placed to talk about the science of gemstones.

One Comment Add yours

Leave a Reply