When shopping for colored gemstones, another question you should definitely ask and one you couldn’t evaluate without a definite honest answer is if the color is natural or applied. There are several commonly used and accepted color treatments that are applied to gemstones in order to change their appearance like heat treatment, irradiation, dyeing, and straining.
Heat Treatment This is the most commonly utilized and one of the oldest treatments for modifying the color of gemstones today. This treatment may use temperature ranging from 100 degrees Celsius to more than 2000 degrees Celsius and improves color distribution as well as reducing visibility of flaws.
Irradiation Low or high electromagnetic waves or energy particles are used to change the color of a given gemstone. Like heat treatment, there is little remaining evidence that could clue a buyer to its use.
With irradiation, certain gemstones have their colors enhanced. Bleached, off-color pearls will obtain a darker tint. Brown or light yellow diamonds can become colored. Light yellow or colorless sapphires may turn yellow to orange, but the change could only last for days. Colorless quartz may turn into smoky quartz. Colorless as well as pale pink and dark blue beryl may become yellow. Time, light, and heat may, however, cause the color for treated beryl jewelry to fade.
Dyeing and Straining This is the major term used to refer to various techniques utilizing a foreign and differently colored substance to modify the color of a given gemstone. A combination of techniques, like dyeing and clarity enhancement for beryl, may be used to improve overall effects. In coating, the application of a second substance is only done on the surface.
Practice makes perfect so browse jewelry shops to familiarize yourself with the various signs that could alert you to the use of applications and treatments on gemstones.
It is also important to understand the clarity and transparency of gemstones. Clarity, together with cut, color, and carat weight, is one of the four important C’s used for evaluating and appraising gemstones. Clarity determines the level of flawlessness of a given gemstone. With great clarity comes great transparency as well. Transparency determines the ability of light to pass through a gemstone and inclusions, which are a no-no in judging quality, can also hinder transparency. Use the following tips to help you evaluate the clarity and transparency of gemstones.
How to Evaluate Clarity in a Gemstone Clarity assesses and grades the external and internal characteristics of a given gemstone. Inclusions such as feathers and crystals are examples of internal flaws. They originate from within but may extend to the surface. Blemishes such as scratches and nicks are examples of external flaws.
Blemishes are generally quite small and only appear on the surface of gemstones. Feathers are cracks or fissures within a gemstone. Crystals are minerals trapped inside gemstones. Inclusions carry greater weight in diamonds than other colored gemstones. While they are expected to occur in certain gemstones like red tourmaline and emerald, inclusions hardly occur in gemstones like aquamarine and citrine.
At times, inclusions and blemishes occur due to the cutting technique utilized. Also, inclusions, at times, increase the value of a gemstone. This is true in the cases of eye in cats eye and stars in rubies and sapphires.
Upon assessing the number, color, nature, location, and size of these flaws, an authorized individual will then grade the clarity of the gemstone on a scale of 0 to 10.
Unlike cut, clarity definitely affects the prices of gemstones.
Types of Gemstones according to Clarity Type 1 These gemstones are free from inclusions most of the time. They include but aren’t limited to yellow beryl, blue topaz, and amethyst. Their grades range from VVS to I.
Type 2 These gemstones generally possess inclusions. They include but aren’t limited to sapphires, rubies, and alexandrite. Their grades range from VVS to I as well.
Type 3 These gemstones are rarely without inclusions. They include but aren’t limited to red tourmaline and emeralds. Their grades range from VVS to I1.