Rubies, like all other gemstones, are evaluated on the basis of their color, clarity, carat and cut. Most buyers find it hard to distinguish between a natural ruby and an artificial one. Due to heavy market demands, the gemstone dealers often supply heat-treated rubies to the buyers. The heat treated rubies are brighter and are found to have less natural flaws. However, the healing properties that a ruby is known for are often missing in the artificial varieties.
Thus it is very important to understand what natural rubies look like, and learn how to distinguish them from the synthetic or heat-treated ones.
1. Hardness test:
Natural rubies are virtually indestructible. With a hardness of 9.0 on Mohs scale, they are closest to diamonds in the gemstone family. They are hardly scratched and remain physically crack-proof for years. If the ruby is scratched by other gemstones, it is definite that the ruby has been artificially polished or irradiated to hide away blemishes.
The rubies show a unique optical phenomenon not visible in other gemstones. Asterism, also called as the “Star effect”, is prominent in rubies cut in cabochons. Considering the fact that the natural rubies are the most stable form of aluminum silicates in the gemstone family, the star effect is rather very prominent. Asterism is mostly seen when a constant streak of light is passed through the gemstone, and it glows like a star. Asterism occurs due to the presence of natural impurities in the rubies. In Blue sapphires and pink rubies, this phenomenon is largely attributed to the Titanium oxide present in the crystal in the form of needles and rutile. Thus, a pure natural ruby is very hard to find, especially if the buyer is looking for a gemstone with flawless clarity.
Synthetic ones reveal only 5% of the star effect that is observed in a natural set.
3. A size of the rubies:
Rubies are mostly available in standard sizes measuring 5mm x 3mm, 6mm x 4mm etc. However, this is only exclusive to rubies cut in oval shape. Calibrated cuts result in sizeable weight loss, which is often considered as a loss for the dealer. Thus, rubies are left uncut or at most given a round brilliant cut.
The size of the rubies decides the color maximization, brilliance, and clarity of the gemstone. Inclusions are often removed by grinding or faceting along the plane that contains the inclusion.
4. Color test:
The finest rubies are neither pink nor red. They are more like scarlet shade, resembling the eye of the pigeon to be exact. However, rubies in other colors like red, orange, brown, burnt brown, grey, champagne, golden and tangerine are also found, and highly revered.
Depending on the hue, saturation, and tone of the color, the value of rubies is established.
5. Misleading terms and genuine certificate:
Buyers are duped by sellers into buying rubies sold with dubious names like balas ruby and rubellite. Some glass crystals, spinels, and quartz are also marketed wrongly as rubies. The heat treatment test is best to identify the pure ruby. However, gem laboratories offer certificate on rubies to benefit the buyers. Always check it.
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