Leonard Joel

Navigating the world of coloured stones and diamonds. What to know before you invest.



Navigating the world of coloured stones and diamonds. What to know before you invest.

Buying coloured gemstones and diamonds can often feel like navigating a minefield! However it doesn’t need to be as complicated and confusing as one may think. Trust your instincts and follow some simple guidelines and the result will be an investment you’ll treasure forever.

1. Coloured gemstones including ruby, sapphire and emerald are judged on their intensity of colour and the clarity of the stone. Look for a stone that has depth and richness of colour. The less inclusions in the stone will add to the value and also to its physical stability. Some surface inclusions can make a stone brittle and prone to chips and cracks. A translucent stone will display more brilliance and purity.

2. The most coveted emeralds are mined in Colombia, premium rubies from Burma and Kashmir being the finest source for sapphires. However many other mines around the world boast magnificent examples of these gems. For example, lot 100 in our Fine Jewels sale is a magnificent Zambian emerald. Deep, rich green and translucent it displays all the qualities you wish to see in a stone of this calibre.

3. Most people have been educated about the 4Cs of diamonds. They are Colour, Cut, Clarity and Carat weight. The higher the quality, the greater the value. What many people may not know about diamonds is that they are the only gem composed of a single element – carbon. Diamonds form under high temperature and pressure about 150 kilometers beneath the earth’s surface. Their carbon atoms are bonded in basically the same way in all directions hence their incredible strength.

4. Some diamonds are described as coloured or ‘fancy diamonds’. What causes these colours? Trace elements. For blue diamonds, it’s boron, for yellow diamonds it’s nitrogen, while green diamonds receive their colour from the earth’s natural radiation.

Our June Fine Jewels auction boasts many fabulous diamond pieces including lot 150, a fancy yellow diamond ring by Anton featuring an impressive 9.71ct fancy light yellow trilliant cut diamond.

5. The rarest of all diamonds is the Type IIa diamond. Only 1% of diamonds mined in the world fall into this category. Chemically they are the most pure and often have exceptional optical transparency. Outstanding diamonds don’t come better than lot 136, a GIA certified 3.52ct emerald cut diamond. Not only is the stone Type IIa, it’s Colour is D (the highest colour grade possible) and it’s Internally Flawless (IF).

We look forward to presenting this beautiful selection of coloured gemstones, diamonds, antique jewellery and timepieces at our Fine Jewels viewings in Melbourne and Sydney.

Elizabeth Stannard
Senior Jewellery Specialist


Sydney Auction
Monday 4 June, 6.30pm

Hughenden Boutique Hotel
14 Queen St, Woollahra NSW

Sydney Viewing
39 Queen St, Woollahra NSW
Friday 1 June, 10am-4pm
Saturday 2 June, 10am-4pm
Sunday 3 June, 10am-4pm

John D’Agata
National Head of Jewellery
03 8825 5605 | 0408 355 339

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