Over the last few years we’ve seen increasing numbers of clients wanting to re-use diamonds from inherited pieces of jewellery to create new engagement rings. The attractions are obvious: re-using an old diamond is a cost-effective way to make a new piece of jewellery while also reaffirming your bond with the person you inherited the jewellery from, and without having to wear something that might not really be your style.
However, re-using an old diamond can present problems. Before you spend money commissioning a new piece of jewellery, how can you be sure that your inherited diamond is good enough to justify the expense? Or even that it’s a diamond at all? With an inherited piece, you might not know which jeweller made it or have any idea where the stone came from.
The natural first step is to check it by eye. Almost all diamonds have natural inclusions or blemishes trapped within the crystal. These might be black carbon specks, white clouding, small feathers (cracks), or bubbles. If you view a diamond under a 10x magnification jeweller’s loupe, you will almost invariably find some minor blemishes even in a good quality diamond. If there are none visible at 10x magnification, then you are either looking at an internally flawless diamond, or a diamond substitute, most likely cubic zirconia.
The next step is to tilt the stone through the light. Diamonds are very hard, and adjacent facets are joined by extremely fine and well-defined edges. This means that when you tilt the diamond, the light will go from falling on one facet straight to falling on its neighbour, without any intervening half-way stage. With a diamond substitute, you will notice the edge between the facets briefly illuminate, as it’s less defined than the edge you would see on a diamond. If you notice this effect, and the stone is completely free of inclusions, it’s very unlikely to be a diamond.
It’s quite possible that a client who has no gemological training won’t feel comfortable judging a diamond by eye. In that case, there are a couple of routes open to them. Firstly, there are electronic devices available that can differentiate between diamond and diamond substitutes based on their thermal and electrical properties. These work instantaneously, and require almost no skill to use. However they can be quite expensive (possibly over £200 depending on the brand), and while they will reliably identify a diamond, they will tell you almost nothing about its condition or its value.
It’s almost certainly a better option to send the stone to a gemological laboratory for inspection. If you were planning to sell the stone, you would ideally have a full certificate. This isn’t cheap, typically costing over £100 depending on the size of the stone. However, if you are planning to re-use the diamond yourself, and all that you need is peace of mind, then some laboratories offer the option of a verbal assessment, which is much cheaper (typically £25 or £30). This will provide you with reassurance that your gemstone is a real diamond, and will offer you a rough assessment of its quality and condition – if there are any chips or surface damage, you will immediately be made aware, and will be able to make an informed decision about how to proceed.