Gemological Tools — How-To Guides

Last updated: September 2026

Reference guides for the instruments used in property-based gemstone identification. Each guide covers technique, calibration, and how to feed the reading into Loupewise.

Choosing Equipment

Equipment

Gem Testing Kit: What to Buy First

All 132 species run through the identification engine to find what a beginner's kit actually narrows. A scale, a magnet and a UV torch leave 8 candidates; a refractometer alone leaves 17.

Read guide →

Instrument Guides

Refractive Index

How to Use a Refractometer

Read refractive index from the shadow edge. Covers calibration, common errors, and interpreting doubly-refractive readings.

Read guide →
Specific Gravity

How to Measure Specific Gravity

Hydrostatic weighing method. Equipment, the weighing formula, and how SG narrows candidates alongside RI.

Read guide →
Calculator

Specific Gravity Calculator

Enter weight in air and weight in water. Get the SG, and the species that value does not rule out.

Open calculator →
Chelsea Filter

How to Use a Chelsea Filter

Transmission filter for emeralds, rubies, tsavorites, and aquamarines. What red vs. green reactions mean — and when they mislead.

Read guide →
UV Fluorescence

UV Fluorescence Testing

Longwave and shortwave fluorescence as diagnostic tools. Species-level patterns and treatment indicators.

Read guide →
Optic Character

How to Use a Polariscope

Reading optic character: the four outcomes, the analyzer-flip confirmation, and the three reasons a stone stays dark.

Read guide →
Inclusions

How to Use a Jeweler’s Loupe

How to hold a 10x loupe and light a stone for inclusions. Silk, two-phase inclusions, fingerprints, and the curved lines that betray synthetics.

Read guide →
Darkfield

How to Use a Darkfield Loupe

What darkfield illumination does, and what the upgrade over a plain 10x loupe is actually worth.

Read guide →
Absorption Spectra

How to Use a Spectroscope

Grating vs prism, the two lighting methods and when each fails, slit discipline, and the practice stones to learn on first.

Read guide →

Using these readings in Loupewise: Loupewise's input panel accepts readings from all of these instruments directly. Enter your measurements and the app filters the candidate list in real time — the orange dot marks the next most useful test to run.