The Gemologist's Toolkit

Identify gemstones with
the instruments you already have.

Start with what you can see — colour, lustre, whether light passes through the stone. Loupewise narrows 132 species to the genuine candidates, then tells you which test to reach for next. Bring a UV torch or a polarising filter and the list gets shorter still; you need neither to start. A photograph identifies nothing on its own; your phone, used as an instrument, does a great deal. Catalog your stones, generate examination reports, and practice for your exams with the same engine.

Start Identifying Free See the Study Guides

No credit card required. 7-day full Pro access.

Practice exams: GIA 20-Stone Gem-A FGA Section D FEEG European Gemmologist
132
gem species & varieties
48
data points per gem
16
instrument & observation categories
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Use on
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Available on iOS, Android, and Web

What’s on the site

Everything here is free to read, no account needed. The measurements behind the app, published as reference.

Specific gravity scale with the measured range of 6 species marked on it: Amber, Rose Quartz, Tourmaline, Topaz, Ruby, Zircon

Property charts

13 charts · sortable

Refractive index, specific gravity, hardness, fluorescence, pleochroism and more — every species in one sortable table per property. Ruby and sapphire share an RI of 1.762–1.770; the charts show what does separate them.

Browse the charts →
One mark for every one of the 132 entries in the database, with the 8 carrying the most look-alikes highlighted

The gem database

132 species · 48 data points each

One page per species — refractive index, specific gravity, hardness, optic character and the rest — what it is confused with, and the test that separates them.

Open a species page →
How many species each instrument class cannot settle on its own, of 132: Dichroscope 68, 10x loupe 25, Refractometer 23, Thermal probe 6

Instrument guides

16 guides · technique and limits

How to take each reading — refractometer, specific gravity, polariscope, spectroscope — what each instrument cannot settle, and which measurement is worth buying first.

Read the guides →
Ruby and Spinel on one refractive-index scale: Ruby 1.762-1.77 (DR), Spinel 1.712-1.736 (SR)

Look-alike comparisons

27 pairs · look-alikes and synthetics

The stones people actually confuse — ruby and spinel, natural and synthetic — side by side, with the reading that tells them apart.

Compare stones →
A finished identification in Loupewise: two candidates remaining from 132

The identification app

16 input categories · free tier, no card

Enter what you measured; the candidate list narrows and tells you which test earns the most next.

Open the app →
20 cells standing for the 20 stones of the GIA practical

Exam study guides

3 credentials · worked practical

What the GIA 20-Stone Practical, the Gem-A FGA Diploma and the FEEG European Gemmologist practical actually ask for, and a full worked example from first reading to written conclusion.

See the study guides →

Three steps to a confident identification

The exact methodology the GIA, Gem-A, and FEEG exams test you on — systematic measurement, narrowing the candidate list, and following test recommendations under time pressure. Covers 132 species, 48 data points per gem.

Candidates remaining after one refractometer reading, across the scale: a median of 15, peaking at 32 rows — but only 11 species — around RI 1.55
1

Enter your measurements

Start with just a refractive index reading. That takes 132 candidates to a median of 15 — fewer at an unusual value, up to 32 where the scale is crowded. Each additional measurement narrows further.

2

Loupewise ranks candidates

The identification engine filters all 132 species against your measurements, flags inconsistencies, and surfaces the most likely identifications with explanations.

3

Follow guided next tests

Loupewise recommends the highest-value test to run next — the one that will narrow candidates most efficiently — and explains what result to look for.

What Loupewise tests

16 instrument and observation categories. Use any combination — Loupewise narrows candidates with whatever you have.

Refractometer
Density / Specific Gravity
UV Fluorescence
Polariscope
Dichroscope
Chelsea Filter
Hanneman Emerald Filter
Spectroscope
Visual Observations
Loupe Observations
Darkfield Loupe
Lighting Observations
Thermal Tester
Magnet Test
Hardness
Context & Specimen

Beyond identification: two-phase origin and treatment testing for 41 gem species, guided step by step with the decision logic at each branch.

What data does Loupewise have for each gem? ▼
Each of the 132 gem entries includes: RI range, birefringence, SG range, hardness, crystal system, optic character, optic sign, pleochroism, UV fluorescence (LW + SW), Chelsea filter, Hanneman filter, color categories, transparency, luster, dispersion, cleavage, fracture type, inclusions (loupe, darkfield, spectroscope), simulants with detection notes, natural vs synthetic tests, and treatment detection tests.
How does the candidate ranking work? ▼
Loupewise runs your entered values against each gem's tolerance ranges. A gem passes if all entered values fall within its documented ranges. Candidates are sorted by how many properties you've confirmed, then by how tightly your measurements fit the expected values. The engine surfaces inconsistencies — if SG is entered but doesn't match a gem that passed on RI, that gem is flagged rather than silently dropped.
Can I use Loupewise with only one or two measurements? ▼
Yes. Loupewise works with partial data. Enter only RI and you'll get a filtered candidate list — a median of 15 entries, depending heavily on the value: an unusual reading can leave two or three, while around 1.55 it leaves 32, which are varieties of just 11 mineral species. Add SG and that list narrows sharply. The engine always tells you which test to run next for maximum narrowing power.

Plans start free

Every account includes a 7-day Pro trial. No credit card required, and the free tier keeps full instrument input on all 132 species and the complete candidate list. See plans and pricing →

Common questions

Can an app really identify gemstones without a photo? ▼
Yes — and more reliably than photo analysis. Gemologists have identified stones by measuring refractive index, specific gravity, and optical properties for over a century. Loupewise applies the same property-based methodology GIA teaches. A photograph captures appearance; RI and SG capture physics. The properties don't change with lighting, polish, or camera settings.
Are these the actual GIA, Gem-A, or FEEG exam questions? ▼
No. Loupewise's practice exams are original practice material built around the publicly documented format of each exam — the number of stones, the timing, and the instrument-and-property workflow you're tested on. The specific stones are ours, not questions from any awarding body. Think of it like a flight simulator: built to match the real conditions, not an actual airline route.
Is Loupewise a substitute for a gemologist? ▼
No. Loupewise is a field identification assistant. It helps you apply systematic, instrument-based methodology — narrowing candidates and planning your next tests. It does not replace professional gemological assessment, laboratory grading, or USPAP-compliant appraisal. Results indicate what a stone is consistent with, not a certified identification.
What happens after the 7-day trial? ▼
Your account stays active with free-tier access: full instrument input on all 132 gems, the complete named candidate list, and 10 drill cards per day. Saved sessions and collection stats unlock at Hobbyist; exam simulators, nat/syn protocols, treatment detection, and examination reports unlock at Pro. No automatic charges — you choose if and when to upgrade. See the full pricing comparison.
What's the difference between Hobbyist and Pro? ▼
Hobbyist ($6.99/mo or $49.99/yr) adds saved sessions, collection statistics, unlimited daily drills, and photo and location capture. Pro ($19.99/mo or $149.99/yr) adds the GIA / Gem-A FGA / FEEG exam simulators, natural vs. synthetic two-phase testing, treatment detection protocols, examination report export, client metadata, and simulant detection guidance. See the full comparison.
Does Loupewise replace a lab report? ▼
No. A Loupewise result is a field identification based on measured properties — it indicates what a stone is consistent with. Laboratory reports from GIA, AGL, Gübelin, or SSEF involve additional testing, documentation, and professional certification that Loupewise does not provide or replicate.

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Support & Account Help
Questions about your subscription, billing, or app behavior. Use the form or email support@gemid-labs.com.
Feature Requests
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