Since ancient times humans have sought to replicate the appearance of rare and valuable materials using alternatives that are more readily available. For centuries this meant using similar-looking materials that were more abundant or man-made options such as glass, but over the last 120 years technological advances have meant increasingly effective simulants and synthetics have entered the market.
With gemstones the definition of a synthetic material is very specific; the stone must have a natural equivalent with the same chemical composition and properties. The synthetic material is essentially the same as the natural but has been grown in a laboratory instead of occurring naturally in the earth. An advantage of this, especially with stones like diamonds and sapphires, is that the synthetic will be as durable as the natural stone and will share some of the properties that make the natural gem so beautiful.
Synthetic gems were first brought to the market at the end of the nineteenth century when the French scientist Verneuil developed his flame-fusion process to grow synthetic ruby and sapphire. Although other production methods have since been developed, this process is still widely used today to produce very affordable synthetic rubies and sapphires in a range of colours. Although the properties of these stones are virtually identical to the natural stones it is usually possible to tell them apart. A first clue is that the colour is often very bright, and the stone has a very clear, transparent appearance, lacking the natural inclusions expected in most sapphires or rubies. Close inspection under magnification may reveal growth features associated with the method of production or tiny bubbles that would not occur in a natural stone. However, increasingly sophisticated production methods mean more stones lack these identification features and require advanced laboratory testing to be 100% sure.
Synthetic sapphires are also grown using several other methods, especially where very pure colourless sapphire is required for use in industry. Since sapphire is so hard it has a wide range of industrial and technical uses, including for the glasses on many wristwatches where it offers a very scratch-resistant upgrade to traditional mineral crystal.
Verneuil’s flame-fusion method is also used to grow synthetic spinel in a very wide range of colours to imitate many different gemstones. Before cubic zirconia became the most widespread and effective diamond simulant, colourless synthetic spinel was used extensively as an affordable alternative to diamond, especially in eternity rings. Adding various elements to alter the colour enables synthetic spinel to be used to imitate most transparent gem varieties. Luckily it is straightforward to identify using ordinary gemmological testing equipment. This is because the optical properties of natural and synthetic spinel are incredibly consistent, and slightly different; close enough that we still regard synthetic spinel as a synthetic gemstone but different enough to be a great help to those wanting to identify it!
Synthetic emerald is grown using a couple of different methods and it is usually possible to identify either of these through close observation. They often display growth features and inclusions associated with the method of production and lack the natural inclusions we would expect to see in emerald. Even more than with sapphire and ruby, synthetic emeralds often appear very bright and transparent in comparison to natural emeralds.
One particularly popular ‘synthetic’ gemstone is opal. This is not truly a ‘synthetic’ as defined by gemmologists, although it is generally referred to as one. The composition and structure is slightly different to natural opal; this difference in structure is useful when identifying it. It can be very convincing and offers beautiful colours reminiscent of fine natural stones that would be very expensive to obtain. In less expensive pieces the stones may be very easy to identify but offer fantastic bright colours that look great in silver jewellery.
In the last few years synthetic diamonds have begun to appear in the market. Diamond is probably the most simulated of all gems through history with most other colourless gems, glass and a variety of other colourless man-made materials being used at one time or another. Synthetic diamond has come into the market so long after other synthetics because the challenge of creating the extremely high pressure, high temperature environment required for diamond to form has been so great. Industrial quality synthetic diamonds have been grown for over half a century but refining the process to produce gems suitable for jewellery has taken time, and techniques are still improving. Modern synthetic colourless diamonds are among the most challenging of simulants to identify with advanced laboratory testing equipment often necessary. This makes independent certification for larger stones more important than ever, and for smaller stones accentuates the need for transparency and trust throughout the supply chain. However, since synthetic diamonds are also reasonably expensive to produce, cubic zirconia (a man-made diamond simulant) is still the preferred choice for inexpensive jewellery.
Synthetic gems can be beautiful and offer an affordable alternative to their natural counterparts. They are also more durable and practical for regular wear than simulants such as glass. However, they don’t have the same amazing story as natural gems. Personal preferences will always vary, but I feel that a substantial part of the beauty of natural gems stems from the fact they are created by the chance interaction of elements in the correct conditions; they are truly a wonder of nature.