Gem Heat Treating

Kandahar Sapphires

The stories of people buying gems in Afghanistan and turning over a sizable profit in the states pass around like rumors, but somebody always knows a relative in the jewelry business. But, there is also the risk of synthetics being tossed into the mix. Not to be confused with heat treatment, this is used to bring out the color in some stones such as rubies or sapphires. Ayoub said when he embarks on a buying trip; it may include places such as Africa, India, Pakistan and Thailand. Recently he traveled to Thailand on a week-long buying adventure to include a two-day course on new treatments for sapphires and rubies and how to identify the treatments, ranging from laser, glass fill, similar to the resin that is injected into the crack in a windshield. Ayoub said that whether you are buying gems as a business or as a consumer, you need to know what you are buying and if it has these new methods of enhancements. During Ayoub’s latest trip to Thailand, after the classes and equipment buying were completed, he joined with a group of buyers he met up in Bangkok for a three-hour southeasterly trip to the border with Cambodia. Chataburi, Thailand is considered the capital of gem buying and is where the entire precious and semi-precious gem stones end up to be cut or sold in large quantities in Southeast Asia. The labor is cheap and has been the focal point for many years. The two dozen or so buyers from mostly Asian countries would have the entire trip arranged by a Bangkok dealer who would facilitate the entire expedition. After arriving at the hotel, the buyers prepare for a three-to-four-day marathon of meeting with hundreds of gem cutters from the region. Beginning with a conference room in the hotel, the buyers would place signs on the front of their tables indicating what they are there to buy, then it begins. Ayoub described the three days as exhausting gem buying, which involves hours of peering through a loop to examine the degree of inclusions (foreign objects trapped in the gem stone), or the tiny imperfections that run like fractures through the gems. In fact they are solid crystal inclusions consisting of calcite, quarts or fluorite, but are expected because they are part of the natural process of their creation. You would expect to find these little fissures that resemble lighting bolts or feathers created under temperatures exceeding 1500 to 1800 degrees Celsius.

Sri Lanka Jewelers: Gem Heat Treatment

All hot objects like the sun, the stars and burning coal radiate energy in the form of electromagnetic waves. Light waves are only a small small part of a wide spectrum of this radiant energy. The gamma rays that come out of radioactive substances are the most energetic of these waves and are used to cure cancers and sterilize food and other items. Less energetic are the X -rays that doctors use to internally examine the body. Lower in energy are the ultraviolet rays that help plants grow and human skin to acquire a dark tan. Even lower in energy are the infrared rays that we cannot see but whose warmth we can feel the warmth as our body absorbs them. Our eyes are sensitive to rays in a narrow range of energies between the heat-giving infrared and the ultraviolet. These visible rays that we generally call "light" cover a spectrum of seven different colours, violet, indigo, blue, green, yellow, orange and red, a range of wavelengths that is commonly termed VIBGYOR and in this range, our eyes are most sensitive to the central region, green. We call those objects that do not give off any radiation 'black' but usually this only means they do not emit visible light. If on the other hand they radiate light of all energies of the visible spectrum, they are usually termed 'white'. The sun whose surface temperature is around 6000C, radiates light with all these colours mixed in a certain proportion. This mixture appears white to the human eye. Artificial light has different ratios of the component colours and thus light from an incandescent bulb appears slightly red while a fluorescent tube produces a blue tinge. So what makes gemstones so luminous and attractive? The beauty comes from the fact that they give out light waves that our eyes can see and to which our senses react. All objects reflect, absorb and emit light that falls on them. Objects like charcoal, that absorb all the light falling on them without any reflection, appear to be black. Conversely, a top quality diamond is colourless but reflects all the light that falls on it and so absolutely accurate only the paper of this book should really be termed 'white'. Between these extremes are the coloured gems that reflect light selectively. A good ruby for instance, absorbs all light but gives off light only in the red region. This is how we recognize and define colour. A transparent medium bends a ray of light that enters it. The more it is bent the higher the refractive index of the medium.

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