Undistinguishable by naked eye
    For high quality synthetic diamonds, it is hardly impossible to distinguish them from the real one by naked eye especially when it is placed on premium quality body.

There are several methods applied for distinguish real diamond from the synthetic one.
     1. Specific gravity (SG): Weigh diamond in concern 2 times to check specific gravity, first time by regular method (in air) and second time while it is in water (weight in water)

Then apply the equation below:
Specific gravity = (weight in air / (weight in air weight in water)
The specific gravity gained from above will be compared with standard specific gravity of diamond at 3.52.

    However, this method cannot differentiate diamond from topaz, quartz, synthetic sapphire and synthetic spinel as specific gravity of these latter gemstones is almost the same to that of diamond.

     2. Refractive index (RI): Use Refractometer and RI Liquids

     3. Thermal conductivity test: Use thermal conductivity probe

This is the most simple and rapid way to differentiate real diamond from synthetic diamond. It can check event such diamond placed on setting but it may have limit capacity for some imitating gemstones.

    Those are some basic methods for checking diamond by scientific instrument. However, new materials or procedures are always discovered or developed in order to imitate diamond and definite conclusion whether it is the real diamond cannot depend on only one instrument.

Therefore, in order to get accurate results, it will depend on expert and scientific instrument.

Why bother buying expensive diamond if you cannot have peace of mind whether your diamond is genuine? Why dont you change to accessories with synthetic diamond that cannot be distinguished by naked eye as it is another option that may be suitable for current economic situation?