Diamond, Moissanite, Swarovski Crystal and Cubic Zirconia
" Diamonds are a girl’s best friend " , a phrase and song made famous by Marilyn Monroe first performed song - simply because we love the sparkling and glittery !
1938 DeBeers launched their advertising campaign “A Diamond is Forever”. The ad campaign is regarded as one of the most successful in history and changed the general public’s perception of diamonds. No longer were diamonds seen as a gem reserved only for Royalty and the highest of society, they came to represent love, affection and faithfulness. Nowadays Diamond engagement rings are not only glamorous they have a very special meaning attached to them, they symbolise commitment and the next chapter in a couple’s life, which combined with their beauty is why they are so desirable.
For years the price of diamonds were kept artificially high by carefully controlling the quantity of diamonds that were allowed to reach the market place by one company who had a monopoly over their distribution.
Today this is no longer the case as diamonds are available from various channels around the world where their price is governed by globalized market economies.
There is still a growing demand for diamonds and with their diminishing supply and extremely high costs other less expensive substitutes are used in their place.
Unlike other gemstones diamonds are formed in the earths mantle a semi-molten layer between the earths outer core and crust that’s subject to extreme heat and pressure. At depths of over 100 miles below the earth’s surface the simple carbon containing minerals were transformed into diamonds by the heat and pressure of their surroundings. All of this happened between 1 billion to 3.3 billion years ago when the earth was much hotter than it is today.
We can’t mine down far enough to reach the earth’s mantle but fortunately volcanic eruptions have done the job for us. The last of these magma volcanic eruptions occurred over 20 million years ago which brought up diamonds close enough to the surface so that they could be mined.
Diamonds are naturally occurring gems that are composed of carbon atoms arranged in a particular structure. They are extremely hard and until recently were regarded as the worlds hardest natural material with a rating of 10 on the Mohs hardness scale. Although diamonds are extremely expensive their price is very much governed by what’s known as the four Cs, carat, cut, colour, and clarity. It’s very rare to find a diamond that doesn’t contain flaws which is why such diamonds demand a high price the same can be said for colour. Most diamonds along with having small amounts of defects or impurities will have a tinge of yellow or brown which is why truly colourless diamonds are so rare.
Diamonds have a high refractive index of 2.417 and a dispersion of 0.044 which means that when light passes from air to a diamond which has a different density to air the speed of light slows down and bends the light due to the angle of refraction. The different colours that make up a white light slow at different speeds and are split up or separate once they enter the diamond. This separation of the colour spectrum is called dispersion and as light leaves the diamond material and enters the air the angle of refraction again bends and the dispersion, which is the separation of white light into different colours (which the light already contains) increases and gives us a colour spectrum.
A Diamond is also an electrical insulator but the best natural thermal conductor known being 4/5 times more conductive than copper. Diamonds have a specific gravity of between 3.5 – 3.53 which is the density of the material in comparison to the same amount of water and is useful for gem identification by gem buyers and gemologists.
Cultured diamonds or synthetic diamonds as they are sometimes called have been in production since the mid 1950’s although the technology could only produce small diamonds. Over the past few years the technology has rapidly advanced and now two companies are able to produce diamonds that are identical in hardness, dispersion, gravity, refraction and chemical composition to the highest quality mined diamonds available. Where as a one-carat top quality diamond would cost thousands of dollars to buy, the same quality man made diamond could be made for less than $ 10.
This will obviously have a huge impact on the diamond industry over the next few years as when comparing a cultured and mined diamond side by side they are virtually undistinguishable, however they can be differentiated by spectroscopy, infrared, ultraviolet, or X-ray wavelengths.
Cultured diamonds can be grown from a single crystal by using a technique called chemical vapor deposition. The technique works by placing cultured crystal seeds in a chamber where hydrogen and methane gases are passed through. The chamber is subject to high heat and pressure which causes hydrogen and methane deposits to collect on the diamond crystals steadily growing them in the process.
Cubic Zirconia is currently the most popular substitute to a diamond because to the untrained eye they look identical. Cubic Zirconia or CZ as it is referred to is made from zirconium dioxide a different material than diamonds, which although a different chemical composition comes closer than any other gem to matching the characteristics of a diamond. Natural CZ was first discovered in 1899 but it wasn’t until the late 70’s that man made CZ first came into production for use in jewellery.
CZ on first impression looks just like a diamond but under close inspection there are differences, it has a gravity of between 5.6 and 6.0 which means it’s 1.6 times the weight of a diamond.
It has a hardness of 8 on the Mohs scale, a refraction index of 2.176 and a dispersive power of 0.060, which means that it’s not as hard as a diamond, it’s slightly less sparkly but displays more prismatic fire which means more colour sparkles within the gem. Another point to note is that natural diamonds display impurities which CZ doesn’t its also clear in colour which most diamonds aren’t, but they can be coloured by adding metal oxides in the production process. Unlike diamonds CZ are good thermal insulators which mean they become warm but can’t withstand the same kind of heat a diamond can, which is one test that is used to distinguish diamonds from CZ.
Caring for CZ is important because they are more brittle than diamonds and susceptible to wear and tear such as chipping and scratches over time.
Moissanite is another diamond substitute which is a rare mineral that can be found naturally in small quantities although jewellery Moissanite is artificially made. It’s made from Silicon Carbide which means it’s able to withstand high temperatures and is very hard with a Mohs scale reading of 9.25.
There is currently only one manufacturer of Moissanite gemstones, Charles & Colvard who have a patent that will expire in 2015. Once the patent expires it will likely become more readily available at a cheaper price when competitors can also manufacture the gemstone. Moissanite is slightly lighter than a diamond with a gravity of 3.21 which isn’t that noticeable but it has a refraction index of 2.65-2.69 and a dispersion of 0.104.
This means that Moissanite is noticeably much sparklier and displays more prismatic fire than a diamond which is noticeable even to an untrained observer. Moissanite does have inclusions like a diamond and it may also have a greenish tinge to its colour.
Swarovski Crystal isn’t a gemstone or even a crystal it’s a form of glass that’s made at high temperatures by melting silicon oxide powders with lead to form what is known as lead crystal. The exact process is one that’s patented by Swarovski but it has approximately 32% lead content to increase the crystals refraction index to resemble that of a diamond. To produce a diamond like effect the crystal glass is precision cut and then polished again by a Swarovski patented process that gives the crystal a high quality finish. The crystals are often further enhanced by coating the glass with an Aurora Borealis or AB coating that gives the surface a rainbow like appearance to simulate dispersion from a diamond. Swarovski crystal has a Mohs hardness of between 6-7 so its susceptible to scratches and chipping from wear and tear but at the same time it’s harder than standard glass. The lead content in the crystal increases the refraction index of the glass from 1.5 to 1.7 to give the faceted faced a more sparkly appearance.
Whichever gem or crystal you decide to use for your jewellery designs you can be sure that any of the above will provide the beautiful sparkle they are all intended for. For most the choice will come down to cost.
Swarovski is undoubtedly the most cost effective diamond alternative. It’s a brand that’s synonymous with quality and elegance which is why it’s used by so many of the top fashion houses around the world both in their designs and in conjunction with promoting their own brand.
Cubic Zirconia on the other hand doesn’t have the brand name as Swarovski, costs slightly more but can offer a more hard-wearing solution for adding a diamond substitute to your jewellery designs.
It’s worth noting that Swarovski make a own CZ range in the meantime.
As we see more cultured Diamonds enter the market and become more readily available it’s likely that we will see a price drop in the genuine article.
Or maybe people will become perfectly happy to accept a man made version in its place because after all it’s appearance also enviromental and ethical awareness isgetting more important .