Wednesday, November 04, 2020

How to look at Sapphires

I love all things bling. So when there was a chance to attend a Sapphire Appreciation Course conducted by Caratell, I was delighted and signed up straightaway. 

This post is not written by a gem expert, but rather, someone who has had little or no prior knowledge about gemstones, so just a disclaimer to experts out there, what you read on below might be more layman and brief!

Caratell is a Luxury Jewellery Store located at 20 Handy Road, Singapore, and have many prestigious accolades under their name, one of them being named the Top Ten Best Jewellers by Singapore Tatler. They specialise in bespoke jewellery design services and of course, Diamonds, Jadeite and Gems.

There are many different types of gems, categorised into precious and semi-precious: Sapphire, Ruby, Emerald and Diamonds fall under precious gems, while Spinel, Opal, Garnet, Peridot fall under semi-precious gems... the list goes on and on. There are various characteristics and factors in play when looking at different types of stones.

However for this session, we focus on what might be the most fascinating yet difficult gemstone to look at: Corundum, specifically Sapphire

Sapphire Appreciation Course

So the course starts with a theory session conducted by Archillea, followed by a practical session with Michael, both, founders of the store.


When you think of Sapphire, you might be reminded of the iconic Sapphire Engagement ring of Princess Diana (now Kate Middleton's), known as the Royal Blue.

Another colour which gem connoisseurs would love, would be the Cornflower Blue. Got this lovely picture of the shade of cornflower blue off the internet:

There's a misconception that Sapphires refers to blue gems, but Sapphires actually come in a spectrum of colours:
  • Blue Sapphire
  • Pink Sapphire
  • Padparadscha (some sort of orange-pink colour)
  • Yellow Sapphire
and so on.. A Sapphire in red colour isn't called a Red Sapphire, but rather a Ruby. 


If you look around, there might be people talking about some specific varieties of Sapphires like the Star Sapphire, where you see an asterism in the stone.

There is also the colour changing Sapphires which exhibits 2 (in rare cases, even 3!) colours in different lightings.

These are 2 examples that Michael showed us under different incandescent lights. See the blue and purple?

And then for this: blue and pink!

Tools needed

First up, you need to learn how to differentiate 2 main things when examining a gemstone:
Synthetic or Natural.

2 very important and basic tools are needed for examining your stones:
  • Refractometer 
  • Microscope

A refractometer allows us to see the Refractive Index (RI) of a stone, and this can be a powerful tool to tell straightaway if a stone is a Sapphire. Just to give examples, Diamonds have single RI while Sapphires have double RI. If the RI falls into a specific range of 1.768 to 1.772, then it would definitely be a Sapphire!

And to further determine whether a Sapphire is synthetic or natural, a microscope will enable us to magnify and check for certain inclusions or characteristics.


There are a few ways that synthetic Sapphires are made:
  • Flame Fusion
  • Flux Growth
  • Hydrothermal
  • Pulling Method
Shall not go into details for that as this post might be super long by the time I'm done elaborating everything about Sapphires!


One of the easiest ways to identify a synthetic Sapphire, is to look out for Curved Striations in the stone.

Tried very hard to search a good picture off the internet but this was the best I could find. If you see somewhat curved lines like these in a stone, it is synthetic. However, I must say, it was difficult to find traces of curved lines in a stone, all the more so if it can only be found in certain areas of the stone, whereby you have to really twist and turn the angles to scrutinize every bit of the stone.


Majority (almost 95%) of natural Sapphires you see in the market are treated, as some sort of treatment enhances the colour or clarity of the gems. 
There are a few ways to do so:
  • Heat
  • Diffusion
  • Glass filled

Sapphires which are glass filled can be seen as the lowest quality of them all.


There will be specific types of inclusions that give evidence to whether a stone is an unheated specimen more easily. 
These includes:
  • Needle 
  • Colour zoning
  • Crystal
  • Snowball
  • Bubble
  • Crack line

Here are some reference photos I found off the internet to let you understand how inclusions look like under the microscope.

Needles, crystals and bubbles are quite easy to spot, while sometimes I might mistake dirt or fingerprints on the stone itself as inclusions. Therefore, it is very important to clean the stone properly before examining it!

So there you have it, this is really just a simple summary of what I went through during the Sapphire Appreciation Course with Caratell.

And here's a cert I got from passing the test from them. Michael gave 1 blue stone to each of us and we had to determine whether that stone is a Sapphire, and if so, whether it is synthetic or natural.

My thoughts and opinions?

There is just so much more to gem appreciation, and I'm glad Michael and Archillea were so accommodating to educate us all about it. Found it very difficult to look at inclusions and differentiate them, especially so if the inclusions look ALMOST the same. 

The engagement ring of Princess Diana also opened the world to Sapphires and paved a whole new way for Royal Blue instead of the coveted Cornflower Blue. 

For the rest of us however, I believe that we look more at the overall design of the Sapphire jewellery piece rather than how little inclusion the stone has, or how it is cut perfectly etc. 

One thing's for sure, we must first learn how to differentiate between a synthetic or natural Sapphire in order to prevent buying knock-offs by inconsiderate sellers out there. Got a friend who almost got duped into buying a Sapphire at a price of a natural, but through the course, found out that the Sapphire the seller was offering turns out to be a synthetic.

And with more experience, we can learn to appreciate the many fascinating things from examining a gemstone. Am glad that Michael is one of those who is passionate on educating to ensure that the Jewellery Industry retains its lustre.

Do visit Caratell's website or social media to get more information on any other gem appreciation courses in time to come!

20 Handy Road, #01-01, Nomu, Singapore 229236