At present, a small percentage of diamonds on the market are synthetic diamonds, which have almost the same appearance as natural diamonds, but can vary in value. Today, we will introduce the difference between synthetic diamond and natural diamond in detail.
Diamond and graphite — pencil leads are mostly carbon
Such artificially produced diamonds are technically called synthetic diamonds and are commonly marketed as “lab-grown diamonds” or “cultivated diamonds”.
High temperature and high pressure diamond rough and finished
High temperature and high pressure method is a method to produce synthetic diamond which simulates the environment of diamond formation in nature. The raw material used is graphite, supplemented with metal catalyst, which is produced in a large tonnage hydraulic press with a heating system.
Because the mold and pressure of the hydraulic press affect the growth of the diamond, the shape of the synthetic diamond produced in this way is different from that of the natural diamond.
Common shape of synthetic and natural diamond rough
But unfortunately, we usually see the cut diamond, even the double-eyed expert without equipment can do nothing, after all, from the appearance of the synthetic diamond and natural diamond is exactly the same.
Synthesis of diamond by chemical vapor precipitation (CVD)
Rough and finished CVD diamonds
The method uses methane and hydrogen gas as raw materials. Carbon atoms in the methane fall onto a diamond film at high temperatures and low pressures to form a synthetic diamond. The blanks formed by this method are usually platelike and completely different from those of natural diamond.
Unfortunately, cut CVD synthetic diamonds look exactly like natural diamonds and are difficult to tell apart.
Next, we will introduce the difference between synthetic diamond and natural diamond from a professional point of view.
No matter how similar a synthetic diamond is to a natural diamond in appearance, professional gemologists with the help of professional testing equipment can identify the different optical and physical properties between the two.
(1) Visible light absorption spectrum
Synthetic diamond: No 415 nm absorption line at room temperature.
Natural diamonds: Most have a 415 nm absorption line.
(2) Ultraviolet fluorescence
Synthetic diamonds: Long waves are usually not fluorescent.
Natural diamonds: mostly blue and white fluorescence at long wave, weak or inert at short wave.
(3) ultraviolet fluorescence image
Synthetic diamond: high temperature and high pressure synthetic diamond luminous image often hourglass shaped growth lines, CVD synthetic diamond visible layered growth lines.
Natural diamond: Occasionally seen ringed growth.
HPHT luminous image of synthetic diamond and luminous image of natural diamond
Finally, remind everyone that in the case of no professional experience, when buying diamonds should ask for professional gemstone identification certificate to avoid losses.