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Diamond Synthesis

Diamond Synthesis was authenticated by General Electric in 1955. Today there are a number of laboratories which synthesizes diamonds, though largely of industrial quality. Since 1970, gem quality diamonds have been synthesized and with the growth of type la yellow diamonds for heat sinks and other industrial uses by Sumitomo Electric Co., it will not be too long before they are available easily.

The Reaction Cell (Flux)

  • The reaction cell is made of pyrophyllite and is inside a carbon tube heater, which is heated by an electric current.
  • Industrial grade synthetic diamond is used as the source of carbon.
  • On each side of this carbon source is a catalyst, such as iron or nickel, which becomes molten on applying high heat and pressure.
  • A temperature differential of about 10-15°C is maintained between the centre and the ends of the cell.
  • The pressure applied to the reaction cell is 60,000 atmospheric pressure (approx. 900,000 psi).
  • The carbon dissolves in the hotter part (1455°C) of the cell, moves through the metallic flux and recrystallises on the seed crystal where temperature is lower (1425°C).
  • These conditions are maintained for several days at 60,000 atmospheric pressure.
  • The pressure is applied in two different ways:
    1. Bert Apparatus Process
    2. Split Sphere Process
  1. Belt Apparatus Process:
    • It consists of giant steel / bars or belts that apply pressure.
    • Reaction cell is placed m a die and swung into a space between two anvils.
    • The pressure is applied from top and bottom while heat is applied from sides.
    • The anvils and die are supported by multiple rings.
  2. Split Sphere Process:
    • It consists of two sets of anvils, on which the pressure is applied.
    • The outer set consists of eight anvils forming a cavity in octahedron form.
    • Inside this set lies a set of six additional anvils.
    • These anvils form a cube shaped central cavity, in which the reaction cell is placed.
    • The pressure is applied by injecting liquid of unknown nature into the compression barrel which applies pressure onto the anvils.

Identification of synthetic diamond

  • Magnification: The characteristic inclusions seen are:
    • Colour zoning in the form of a square or rectangle, the central area being surrounded by darker coloured areas.
    • Graining - Rectangular or octagonal shaped internal graining lines projecting outward from each corner.
    • Metallic Inclusions - Large rounded or elongated inclusions with a metallic lustre, numerous pinpoint inclusions.
  • Ultra Violet Lamp: Green / Yellow Luminescence in both the waves.
  • Spectroscopy - Moderate absorption band between 450 and 500nm, weak bands between 470 and 600nm.

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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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