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Gemstones

Sunday, 21 June 2009

Diamonds, rubies, sapphires, oh my! While sparkly gems like these may be out of many people's budgets, there are more affordable and just as fabulous options to consider. Semi-precious gems including amethyst, aquamarine, citrine, garnet, peridot, topaz and tourmaline are some of over 3000 minerals used in jewelry. We find out more about these great alternatives.

The Basics

  • Gemstones are cut and shaped to enhance their natural beauty. The value of gemstones is measured based on the beauty, rarity, durability, and desirability.

  • Popular gemstones include:

    • Amethyst (February birthstone) is crystalline quartz occurring in shades of purple, from lilac to mauve, and originating from Brazil, Uruguay, Bolivia, Mexico, Zambia, the US and Canada.

    • Aquamarine (March birthstone) gets its colour from iron. Most gemstones have been treated to enhance the blue-green colours from the yellow or pale colour as many are found. The richer the blue, the more valuable. Brazil produces most aquamarines, with Pakistan and the US also carrying prize specimens.

    • Citrine (November birthstone) is yellow-orange quartz. It is actually rare in nature, and most on the market have been heat-treated to produce the colour. (Low grade amethyst is ” cooked”to produce the desirable citrine colour. Natural stones are a pale yellow, whereas heat-treated stones are more orange or reddish-yellow.

    • Topaz, also November’s birthstone, is similar to citrine, but much more expensive. (Citrine is sometimes falsely sold as topaz.) Topaz has a gold-brown to yellow colour. Blue topaz, rare in nature, is often confused with aquamarine and is produced by irradiating and then heating clear crystals. Topaz comes from Brazil, Mexico, Sri Lanka, Africa, and China.

    • Garnet is January’s birthstone and is hard, glassy, and available in a variety of colours and price ranges, though is commonly thought of as red and can be sold as imitation ruby. Most garnet gemstones are mined in central Europe, Russia, and South Africa, but small garnets can be found in Canada in areas where gold occurs (e.g. BC.)

    • Peridot (August’s birthstone) comes from the mineral olivine and is olive or light green in colour. Good quality peridot is rare, and is mostly mined in Arizona, but new discoveries in Pakistan that produce quality specimens is giving peridot a boost in popularity.

    • Tourmaline, October’s birthstone, comes in a wide array of colours, from pinks to reds to greens to blues. Tourmaline is often heated or irradiated to enhance the colours, and is mined in Brazil, Afghanistan, East Africa, and the US.

  • To identify quality of a gemstone, look at the 4 C’s as well as a few other characteristics:
    • Clarity: look for stones that are glassy-clear, with no blemishes, cracks, or internal inclusions.

    • Colour should be vivid, even, and uniform throughout the entire stone.

    • Cut, or how it has been shaped, should highlight the best features of the stone. Types of cuts include:

      • Cabochon: flat on the bottom and rounded on the top, often used for dark stones or translucent/opaque stones. They can be round, oval, square, triangular, and even octagonal in shape.

      • Faceted: the most commonly known cut for gemstones, facets are flat surfaces cut all over the gem that reflect and absorb light to give it a sparkle effect. Different styles of facet cuts include brilliant, step cuts, mixed cuts and fancy cuts. A jeweller should be about to make suggestions for the best cut style depending on the features of your stone.
    • Carat is the weight of the stone.

    • Lustre is the overall appearance of the stone, the way light reflects from its surface. If it is mirror-like, it is described as “splendent”. It will have a more earthy or dull lustre if less light reflects from the surface.

    • Refractive index (RI) is measured by a professional with a refractometer tool, which calculates the speed and angle of light as it passes through the stone.

    • Natural inclusions are internal features like cleavages, cracks or fractures that can either make the stone more interesting, or make it less valuable due to flaws.

  • Authentic gemstones often undergo a variety of treatments called enhancements, which hide cracks and flaws, and bring out colour. For example:

    • Heat is used to change or intensify colour or clarity

    • Staining with dye or chemicals can alter the appearance and enter the cracks and flaws

    • Irradiation changes and enhances the colour, but may fade over time.

    • Oiling is a common practice that is done to enhance colour, creating a more permanent “wet” look. It also disguises unwanted fissures and blemishes.

    • Foiling, an undesirable practice, is when a closed-back setting is lined with coloured foil to make the gemstone take on the colour of the foil. This is usually because the stone is poor quality. If you see a closed setting, beware!

   Be Aware

  • Not all gemstones are natural. Synthetic gemstones are made in labs or factories and don’t come from rocks. Imitation gemstones are man-made and usually intended to deceive. Make sure you are working with a reputable jeweller and ask for a certificate of authenticity.

TEST CRITERIA

We selected six stones and took them to a reputable gem specialist to find out if they could spot the fakes.

  • Blue Topaz: $400
  • Aquamarine: $800
  • Synthetics: all under $50

Gem-Spotting Test

  • To us, telling the difference wasn’t easy. The differences between expensive aquamarine and blue topaz compared to the others was almost indistinguishable with our naked, untrained eye.

  • We learned that topaz has a more slippery texture than aquamarine, so using the touch test, we were able to distinguish between the two once we learned the trick.

  • We also learned that you definitely need to have an expert on your side. Kristina found out that an aquamarine ring she bought in Greece was actually a fake!

 

 

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