Laboratory
A gem lab has a collection of equipment allowing the gemologist to thoroughly inspect jewelry and gemstones, determine and grade its qualities, calculate measurements, and arrive at an estimation of value.

The following list of equipment can give you an idea of what may be used in identifying and appraising jewelry and gemstones. These are basic laboratory equipment and some or all of it may be used in any specific appraisal.

Binocular 10-power microscope with dark field illuminator Diamondlite or color grader Dichroscope Fiber optic lighting Filters and lenses Leveridge gauge, millimeter gauge, calipers, and ruler Long and short wave ultraviolet lights Diamond Master set Master set of colored stones or color communication system Metal testing acids and gold tip needles Penlight Photographic equipment Polariscope with interference figure sphere or lens Proportionscope Refractometer Scale, preferably electronic, that gives weight in carats, grams and pennyweight, to .001 Spectroscope Specific Gravity Scale Thermal conductivity tester

Gemstone Identification
Using equipment in a gem lab, gemologists rely on four basic tests for gem identification.

• Hardness
  The Mohs scale is used to rate mineral hardness. The higher the number, the harder a mineral is to scratch. Each mineral can scratch other minerals having equal or lower Mohs ratings. The hardest is diamond, which scores 10 on the Mohs scale. Corundum (that is, ruby and sapphire), scores 9, meaning diamond is 100 times harder than sapphire or ruby. The softest is talc, with a Mohs rating of 1.
• Specific Gravity
  This is the ratio of the density of the gem to that of water at 4 degrees C.
• Refractive Index
  This is a measurement of the amount a light ray is bent as it enters or leaves a gemstone, expressed numerically.
• Microscopic and Loupe Examination
  The gem is viewed internally from different perspectives using a microscope or a loupe at 10-power magnification.

Gemstone Toughness & Hardness
A gem’s toughness should not be confused with its hardness.

Toughness means resistance to breaking, chipping or cracking — in general, how well a stone holds up under mechanical stress, such as impact from a fall. Toughness rating is usually stated as exceptional, excellent, good, fair, or poor.

Hardness refers to how resistant a mineral is to scratching. It is described as a score between 1 and 10 on the Mohs scale.

Diamond, for example, is the hardest mineral, with a Mohs rating of 10, but its toughness rating is only good. Hematite, on the other hand, has an excellent toughness rating, but its hardness is only between 5.5 and 6.5.