Olive Oil and Diamonds
The earliest diamond cutters shaped jewels with the help of other diamonds and additional materials. By rubbing two stones together, they evened the sides of the gems and produced ground dust which was recycled for polishing still more diamonds. Polishing wheels operated under a similar principle, using ground gems as abrasives. To help keep the diamond dust under control and adhered to desired surfaces, cutters used olive oil.
Modern people may find diamonds and olive oil to be a strange combination, associating the latter with cooking or cosmetics. Making the pair seem more incongruous is that grease can diminish the brilliance of diamonds. When oil sticks to a diamond, it alters the way light interacts with the stone, causing light to leak from the sides rather than reflecting through the jewel’s top.
Whether it’s by rubbing two stones together or utilizing a polishing wheel, the friction involved produces large amounts of heat. Olive oil has strong heat tolerance, with a smoke point of 300 degrees Celsius, or 575 degrees Fahrenheit. This in turn allowed early gem cutters to work with little fear of the grease impacting their equipment or degrading.
To transform a diamond from a piece of rough to a masterpiece of brilliance doesn’t happen immediately. This is partly due to diamond’s hardness, which makes cutting a challenge. A jewel that receives consideration and planning before and during cutting is more likely to be attractive than one that’s formed in haste. Many steps occur before a diamond is faceted.
Very few diamonds are without clarity characteristics. While some add to a diamond’s beauty, others may make a diamond prone to damage as it’s cut or afterwards. Due to crystal structure, diamonds are easier to cut in some directions than others, though it’s not always clear which way is which on a rough. Before a diamond is cut, it’s plotted, or examined for optimal ways of cutting. This can impact the chosen cut of the stone, its carat and even how many cut diamonds are made from the piece of rough.
After the gem is plotted or marked, the diamond may be cleaved. This divides the stone by hitting it along one of its cleavage planes, where the jewel’s atomic bonds are weakest. Before the gemstone is cleaved, it has a notch cut into its rough, known as a kerf. A blade is placed into the kerf, and a hammer taps the arrangement until the jewel splits.
Another way to separate a diamond is with saws. This method allows cutters more freedom with how they choose to divide the stone rather than depend on cleavage planes. With rotary saws, which have blades treated with diamond dust, cutters are able to take advantage of sawing planes, which are difficult to cleave. Laser saws may cut any which way, without having to worry about direction.
The next step is bruting. Here the rough takes on a shape closer to that of a finished jewel. For abrasive purposes, two diamonds must be used for this process. One or both gemstones are fastened to a lathe. As the machine whirls, the diamonds touch one another, grinding into the desired shape. With some versions, both diamonds brute one another, while other methods use a stone purely for polishing other jewels.
As rotary machines are commonly used for this purpose, bruting usually applies to round diamonds rather than other shapes. Since the early 1990s, laser bruting has served as an exception. With this technology, curved fancy cuts such as marquise cuts may also be shaped with this method.
After all this preparatory work, the diamond is now ready to be faceted. This too takes multiple steps to help ensure that the jewel is symmetrical and faceted as carefully as possible. Bringing out the best in a diamond is a slow journey. By taking time to plan, divide and shape the stone, it’s easier to facet the best possible jewel.