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Colour
  • Color and transparency: heat treatment (partially) dissolves fine rutile needles thereby increasing the clarity, transparency and remove brownish components
  • Color strengtening: diffusion of colour causing elements through intense heating
  • Color: surface reaching fissures may be treated with oil or dyes, resulting in stronger colours. Treatment not durable and requiring special care
  • Improving transparency: lead glass filling in cavities and fissures
Clarity
  • "Silk," networks of fine, included rutile needles, intersecting at 60 degree angles, are commonly seen in natural ruby
  • Included crystals of zircon, and related stress fractures (or halos) are sometimes seen. Liquid-filled "fingerprint" inclusions are also common
  • Note some of these identifying characteristics may disappear, change or be diminished as a result of treatments
  • The presence of silk or other inclusions is often valued since it not only points to a gem's natural origin but it also suggests the gem has not been treated


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TREATMENTS
CUT
  • Transparency: heating dissolves or partially dissolves fine rutile needles thereby increasing the clarity and transparency of the gem. 
  • Transparency: High lead content glass is sometimes used to fill surface reaching fissures, pits or cracks in certain rubies/ corundum increasing transparency
  • Color: heating helps remove purplish or brownish colour components in some gemstones, resulting in stronger red colours
  • Color strengthening: diffusion of colour causing elements through intense heating
  • In the market, rubies are found in a variety of shapes and cutting styles
  • Ovals are cushions are the most common, but rounds are also seen, as are other shapes, such as the heart or emerald cut
  • Slight premiums are paid for round stones, while slight discounts apply for pears and marquises
  • Stones that are overly deep or shallow should generally be avoided



Care

Rubies are extremely durable due to their hardness and toughness - second after diamond on the Mohs Hardness Scale. Ruby jewellery may be cleaned in an ultrasonic cleaner, or it may be steamed. But this should follow close inspection to determine if there are any surface reaching fissures that could expand, or if oils or dyes are present. As with most gemstones, a soft moistened cloth, or a soft bristle toothbrush may be used to clean the gem
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