About to spend a bomb on a piece of jewellery? Afraid that your trusted jeweller really isn’t to be trusted?

Now, there is a way to see for yourself that those rocks you bought aren’t worthless pieces of glass, and that your precious metal is not more copper than gold.

Calcutta has its first “jewellery lab” where anyone with a piece of jewellery can check the exact amount of gold in it, and the true value of stones, measured by carat, colour and clarity. The set-up at Sawansukha Jewellers, a seven-generation-old store, is housed within the first-floor store on Ho Chi Minh Sarani and is free to be used by all.

“Anyone wishing to check either their old or newly-bought jewellery is welcome. We have not restricted the use to only those customers who buy from us,” says Siddhartha Sawansukha, a gemologist from the Gemological Institute of America, and the brain behind this offering.

The lab consists of three pieces of equipment. The gold testing unit, which looks like a tiny photocopying machine, can detect the amount of copper and silver mixed with the yellow metal.

A microscope helps identify the clarity of diamonds. “The process of examination is easy, and we can instantly educate the crowd about how to use it,” explains Sawansukha. An accompanying chart shows the various grades of diamonds, helping customers identify a diamond of good quality.

The third instrument in the lab, called the Diamond Grading Machine, helps grade loose diamonds on the basis of colour. “Diamonds are colourless to yellowish in shade, depending on quality,” adds the jeweller.