Inorganic Gemstones

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Brilliance

It is defined as the intensity of the light that enters the eye after internal and external reflection from the cut gemstone. It is best explained by the terms life, fire and scintillation.

  • Life: Incident white light which is reflected as white light only from the surface and from the total internal reflection, of light from its pavilion facets is known as life.
  • Fire: Reflection observed as spectral colours is known as fire.
  • Scintillation: It is the multiple and alternating reflections of light from the facets of a polished gemstone, when there is a relative movement between the observer and the light source or the gemstone.

Brilliance depends on a number of factors:

  • Polish
  • R.I. (critical angle)
  • Transparency
  • Proportioning, in terms of number and size of facets and their cutting angles.

A cutter must keep in mind that to obtain maximum brilliancy from a gemstone it must be cut in proportions that will cause the greatest possible amount of light entering the stone, to be totally reflected from the pavilion facets and to pass out through the crown facets.

The light which enters the stone must strike the pavilion facets at:

  • angles greater than the critical angle to be totally internally reflected.
  • then strike the crown facets at angles less than the critical angle to be refracted out and returned to the observer. This is also known as planned leakage of light.
  • Light striking a pavilion surface at an angle less than the critical angle will be refracted out of the stone and is this lost to observer, thereby reducing its brilliance. This is known as unplanned leakage of light. This is observed in diamonds clearly in terms of a lumpy stone (deep pavilion) and fish eye (shallow pavilion) stones.

Did you know?

Jewellery is one of the most bought products online. An estimated $1 billion USD of diamonds are bought annually via the Internet. Over 40 million people use the Internet to trade!

In Germany, the garland of ambers is hung around the necks of the infants, so that their teeth might come out without much trouble.

In Turkey, people fix a piece of amber in the hubble-bubble, dogged by an age old belief that the presence of the jewel would destroy all the germs and no disease would spread, even after many have dragged their puffs from it.

In Greece, people think if wine is poured into the cups made of amethyst, one does not get drunk after drinking that.

In Rome, a talisman having coral pieces is considered very auspicious to quell the bad spells of evil look. The Romans were in the habit of hanging chains made of ancient coral pieces from the cradle of the infants to protect them from evil effects.

In China, people wear rings studded with tiny conch or oyster shells as they believe it cures all aches such as stomach ache, worms and like.

In India, pendants made of silver and studded with pearls are hung from the necks of the children to save them from any bad effects.

Greeks still believe, if women wear blue sapphires then no sense of immorality would pollute their mind nor can any fear of the supernatural can trouble them.

The Pope Innocent III had circulated an order asking all the priests wear blue sapphire, so that morality can be strengthened.

It is said about turquoise, that when the stone changes its color into yellow, it actually signals bad times to the person who wears it.

It is believed that a turquoise gifted to a friend or a lover turns his or her life into one of happiness and good luck.

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