A gem and Rudraksha testing laboratory is a smaller place than most people imagine. The instruments fit on a bench; most of them are the size of a hand or a small box; the X-ray unit is the largest thing in the room. Each one answers a specific question, and the examination is a sequence of those questions. This is what sits on the bench and why.
Balance
An electronic balance reading to 0.01 g, or a carat balance reading to 0.001 ct. The first thing every article meets. Weight identifies the article for matching and is half of the specific-gravity measurement. A hydrostatic attachment — a bridge and a beaker of water — lets the same balance weigh an article immersed. Specific gravity: weighing a stone against water.
Digital gauge and calliper
Measures to a tenth of a millimetre. Dimensions go on the report for matching and, for beads and spheres, give the volume used in density estimates.
Stereo microscope
The centre of the bench. A binocular microscope at 10× to 60× with darkfield illumination (light from the side, so that inclusions glow against a dark background), brightfield, overhead light, and often an immersion cell. It examines the surface of a Rudraksha — groove floors, seams, texture — and the interior of a gemstone — inclusions, growth features, filling, dye. It is the instrument that decides natural versus synthetic and treated versus untreated. Inclusions: the fingerprints inside a gemstone.
10× loupe
The portable microscope. Used for a first look at everything, for reading inscriptions, and for anything too large or awkward for the microscope stage.
Refractometer
Measures the refractive index of any stone with a flat facet, to three decimal places, in under a minute. The single most decisive instrument for gemstone species. Needs a contact liquid and a light source, and a monochromatic filter for precision. Refractive index: the most important number in gem identification.
Polariscope
Two crossed polarising filters over a light. Tells whether a stone is singly refractive (garnet, spinel, glass), doubly refractive (most crystals) or an aggregate (chalcedony, jade). With a conoscope lens it shows interference figures. Ten seconds per stone. Polariscope and dichroscope.
Dichroscope
A small tube that shows whether a coloured stone displays two colours in different directions — pleochroism. Separates ruby from garnet, sapphire from spinel, and flags dye.
Spectroscope
A hand instrument that spreads the light passing through a stone into a spectrum and shows absorption lines. Identifies the colouring element — chromium, iron, cobalt, rare earths — and catches dye and cobalt glass. The spectroscope.
Ultraviolet lamp
Long-wave (365 nm) and short-wave (254 nm) UV in a darkened cabinet. Reveals fluorescence that separates some naturals from synthetics, shows resin and adhesive in joined beads and filled stones, and reveals some treatments. UV fluorescence in gem testing.
X-ray unit
A small cabinet radiography unit — of the type used in dentistry or industrial inspection — with a digital detector. Images the internal compartments of Rudraksha and the nucleus of pearls. Shielded; the operator stands outside; the exposure is a fraction of a second. The instrument that settles mukhi counts, joined beads and cultured pearls. How X-ray testing of Rudraksha works.
Thermal and electrical conductivity tester
A probe that separates diamond from cubic zirconia (thermal) and moissanite (electrical). Used for diamond screening. Diamond, moissanite and cubic zirconia.
Camera
Every article is photographed for the report and the register. For Rudraksha, a monochrome high-contrast image emphasises surface structure; for stones and other articles, colour under standard lighting.
What is not on a routine bench
Spectrometers (FTIR, UV-Vis, Raman), trace-element analysers (LA-ICP-MS, EDXRF) and photoluminescence equipment are the instruments of large laboratories and are needed for low-temperature heating detection, beryllium diffusion, lab-grown diamond confirmation and origin determination. A routine laboratory knows the questions that need them and says so on the report. What a laboratory report cannot tell you.
Frequently asked questions
How long does an examination take?
A routine Rudraksha or gemstone identification takes from ten minutes to half an hour on the bench, plus documentation.
Can I see the instruments?
Most laboratories will show their bench on request. Asking is reasonable. Questions to ask any testing laboratory.
Is the X-ray unit the same as a medical one?
Similar in principle, smaller in scale — closer to a dental unit — and used on objects, not people.
Which instrument is most important?
For gemstones, the refractometer and the microscope together. For Rudraksha, the microscope and the X-ray unit.
Do instruments need calibration?
Yes. Refractometers are checked against reference stones; balances against standard weights; X-ray units are serviced and inspected. A laboratory should be able to say how.