How to Buy a Diamond

Part of Buying Gemstones For Dummies Cheat Sheet (Australian Edition)

Mostly people buying gemstones are interested in looking at diamonds: They’re still the favourite. When you’re buying diamonds or shopping for diamond jewellery, you should always take a jewellery or hand loupe with you or borrow one from your jeweller. Clean the diamond thoroughly before you look at it with a soft cloth.

These are the things you need to ask your jeweller when buying a diamond:

  • Is it a natural diamond and not a synthetic or imitation? Natural diamonds have formed at great depths in the Earth’s crust, at extremely high temperatures and pressures, and have taken many millions of years to do so.

    Certain substances have been substituted for diamond, such as cubic zirconia (CZ) and synthetic moissanite; as well as zircon; glass; synthetic rutile, sapphire and spinel; and man-made garnets like GGG and YAG.

  • Can you guarantee that it’s not a conflict diamond? Conflict diamonds, also known as ‘blood diamonds’, are natural diamonds which have been illicitly mined and sold to finance wars and civil unrest, mainly in certain African nations. Ask your jeweller if he or she can provide you with a Kimberly certificate, which states that a diamond’s sale has not financed war. Diamonds mined in Australia or Canada are not blood diamonds.

  • What is the diamond’s exact grading: carat weight, colour, clarity and cut? Diamond quality is graded by reference to the 4Cs — carat weight, colour, clarity and cut. Diamonds are weighed in carats (1 carat = 1/5 of a gram), or in points (100 points = 1 carat) for smaller diamonds. Most people think of diamonds as ‘white’ or clear, but diamonds come in many colours.

    Generally, the ‘whiter’ the diamond the better, unless you are fortunate enough to have an intense fancy coloured diamond. Clarity refers to freedom from internal inclusions and external flaws, and the cleaner a diamond is the better. A diamond usually sparkles best with a brilliant cut, which was designed especially for diamonds.

  • Has your diamond been clarity enhanced? Some diamonds are clarity enhanced usually by fracture filling and laser drilling. Fracture filling involves filling cracks or breaks with a colourless substance to hide them. Laser drilling is used to make inclusions less visible and so improve a diamond’s look. Ask your jeweller whether a diamond has been clarity enhanced and, if so, how.

  • What is the shape? The term ‘cut’ does not refer to shape. Shape refers to the outline of a diamond’s edges. A diamond may be round, square, rectangular, marquise, pear, trillion or heart shaped. Whatever its shape, the quality of the cutting must be judged, too.

  • Does it have a good ‘make’ (proportions)? The term ‘cut’ is also referred to as a gemstone’s ‘make’. When you judge cut, you’re really considering a gemstone’s proportions and finish. It is these two factors that determine a diamond’s fire (flash) and brilliance (life), no matter what cutting style or shape. In a well-proportioned diamond, the height of the crown should be a third of the pavilion depth.

  • What are the exact millimetre dimensions of the stone? When buying gemstones you should be told its exact dimensions in millimetres (size), in addition to its carat weight.

  • Is the diamond accompanied by an independent grading report? An independent grading report is an objective assessment that identifies and describes an unmounted diamond. However, it is neither a legal certificate nor an appraisal, which gives a subjective value or price attached.

    Most independent grading reports include the date; type of gemstone; shape and cutting style; weight; dimensions; proportions (depth, table, crown, pavilion, girdle, culet); colour grade; clarity grade; cutting and finish (polish and symmetry) quality; fluorescence; and diagrams showing inclusions (types and locations).