- Treatment detection requires correlating multiple lines of evidence. Heat treatment
- in corundum leaves characteristic stress fractures around rutile inclusions and
- healed fingerprints, but not all heated stones show these features — a clean,
- well-heated stone may show no internal evidence at all. Fracture filling in emerald
- suppresses the fingerprint inclusions that would otherwise be visible under
- magnification, but the filling material itself can be identified by its flash effect
- and RI mismatch with the host. Diffusion treatment in sapphire concentrates
- colour at the surface, visible as concentrated colour at facet edges when the stone
- is immersed. Each treatment leaves a different combination of positive and negative
- evidence, and confident treatment assessment depends on accumulating independent
- observations rather than relying on any single clue.
-
-
- The treatment wizard on this page formalises this evidence-accumulation approach.
- It covers 18 observable clues — including inclusion type, surface texture, colour
- distribution, spectral absorption anomalies, fluorescence pattern, and magnification
- features — mapped against 11 treatment categories: heat, fracture filling, surface
- coating, diffusion, irradiation, oiling, waxing, bleaching, impregnation, laser
- drilling, and flux healing. Each clue carries positive or negative evidence weights
- for each treatment type. Submit the clues you have observed and the wizard sums the
- weights per treatment, producing a confidence-banded conclusion — high confidence
- when three or more independent indicators align, low confidence when evidence is
- mixed or a single clue stands alone. This mirrors the reasoning process used in
- major gemmological laboratories and makes the logic explicit rather than implicit.
-
-
- The proportion analyzer applies a different kind of multi-parameter assessment to
- cut quality in round brilliant diamonds. The GIA cut-grade system evaluates seven
- proportions independently: table percentage, total depth percentage, crown angle,
- pavilion angle, girdle thickness, culet size, and star length. Each parameter falls
- into one of five grade bands (Excellent, Very Good, Good, Fair, Poor) according to
- published GIA thresholds, and the overall cut grade is determined by the
- lowest-grading individual parameter. Enter the measured proportions from a
- proportion scope or grading report and the tool displays the per-parameter band for
- each value, highlights the limiting parameter, and returns the resulting cut grade.
- Understanding which proportion is pulling the grade down — crown angle too shallow,
- table too wide, or girdle too thick — gives a precise basis for cut-quality
- assessment and client communication.
-
-
+
+
+ About these advanced tools & methodology
+
+
+
+ Treatment detection requires correlating multiple lines of evidence. Heat treatment
+ in corundum leaves characteristic stress fractures around rutile inclusions and
+ healed fingerprints, but not all heated stones show these features — a clean,
+ well-heated stone may show no internal evidence at all. Fracture filling in emerald
+ suppresses the fingerprint inclusions that would otherwise be visible under
+ magnification, but the filling material itself can be identified by its flash effect
+ and RI mismatch with the host. Diffusion treatment in sapphire concentrates
+ colour at the surface, visible as concentrated colour at facet edges when the stone
+ is immersed. Each treatment leaves a different combination of positive and negative
+ evidence, and confident treatment assessment depends on accumulating independent
+ observations rather than relying on any single clue.
+
+
+ The treatment wizard on this page formalises this evidence-accumulation approach.
+ It covers 18 observable clues — including inclusion type, surface texture, colour
+ distribution, spectral absorption anomalies, fluorescence pattern, and magnification
+ features — mapped against 11 treatment categories: heat, fracture filling, surface
+ coating, diffusion, irradiation, oiling, waxing, bleaching, impregnation, laser
+ drilling, and flux healing. Each clue carries positive or negative evidence weights
+ for each treatment type. Submit the clues you have observed and the wizard sums the
+ weights per treatment, producing a confidence-banded conclusion — high confidence
+ when three or more independent indicators align, low confidence when evidence is
+ mixed or a single clue stands alone. This mirrors the reasoning process used in
+ major gemmological laboratories and makes the logic explicit rather than implicit.
+
+
+ The proportion analyzer applies a different kind of multi-parameter assessment to
+ cut quality in round brilliant diamonds. The GIA cut-grade system evaluates seven
+ proportions independently: table percentage, total depth percentage, crown angle,
+ pavilion angle, girdle thickness, culet size, and star length. Each parameter falls
+ into one of five grade bands (Excellent, Very Good, Good, Fair, Poor) according to
+ published GIA thresholds, and the overall cut grade is determined by the
+ lowest-grading individual parameter. Enter the measured proportions from a
+ proportion scope or grading report and the tool displays the per-parameter band for
+ each value, highlights the limiting parameter, and returns the resulting cut grade.
+ Understanding which proportion is pulling the grade down — crown angle too shallow,
+ table too wide, or girdle too thick — gives a precise basis for cut-quality
+ assessment and client communication.
+
- The metric carat was standardised internationally in 1907 at exactly 200 mg
- (0.2 g). Before that date, the carat varied by country — the old English carat
- differed from the French, which differed from the Turkish — making gem weights in
- historical records difficult to compare. The 1907 standard fixed the unit absolutely,
- and today a 1.00 ct stone means the same weight in every country. In trade, the
- carat is subdivided into 100 points: a 0.50 ct stone is described as
- fifty points, a 0.35 ct stone as thirty-five points. The weight converter on
- this page handles carats, grams, milligrams, grains, and troy ounces — the full
- range of units encountered when reading historic inventory records, laboratory
- reports, and customs documentation.
-
-
- Length conversion between millimetres and inches is a routine need when gem
- dimensions measured with a metric caliper must be communicated in markets that use
- imperial measurements, or when a published cutting diagram gives proportions in
- inches that must be scaled to millimetres before use in the carat estimator. The
- conversion is straightforward (1 inch = 25.4 mm exactly), but having a
- dedicated converter eliminates the mental arithmetic error that can occur when
- managing multiple measurements at once.
-
-
- Temperature conversion matters in two specific gemmological contexts. First, the
- specific gravity calculation depends on the density of water at the temperature of
- the liquid used during hydrostatic weighing: water is densest at 4 °C
- (1.0000 g/cm³) and becomes measurably less dense as temperature rises,
- reaching 0.9957 g/cm³ at 30 °C. The SG calculator on the
- Measurement page applies this water-density correction automatically, and the
- temperature converter here lets you enter a Fahrenheit reading from a lab thermometer
- and obtain the Celsius value needed for that correction. Second, some refractometer
- reference tables and refractive index databases list temperature coefficients in
- Fahrenheit; converting to Celsius before applying a temperature correction to an RI
- reading ensures the adjustment is applied in the right direction and magnitude.
-
-
+
+
+ About these converters
+
+
+
+ The metric carat was standardised internationally in 1907 at exactly 200 mg
+ (0.2 g). Before that date, the carat varied by country — the old English carat
+ differed from the French, which differed from the Turkish — making gem weights in
+ historical records difficult to compare. The 1907 standard fixed the unit absolutely,
+ and today a 1.00 ct stone means the same weight in every country. In trade, the
+ carat is subdivided into 100 points: a 0.50 ct stone is described as
+ fifty points, a 0.35 ct stone as thirty-five points. The weight converter on
+ this page handles carats, grams, milligrams, grains, and troy ounces — the full
+ range of units encountered when reading historic inventory records, laboratory
+ reports, and customs documentation.
+
+
+ Length conversion between millimetres and inches is a routine need when gem
+ dimensions measured with a metric caliper must be communicated in markets that use
+ imperial measurements, or when a published cutting diagram gives proportions in
+ inches that must be scaled to millimetres before use in the carat estimator. The
+ conversion is straightforward (1 inch = 25.4 mm exactly), but having a
+ dedicated converter eliminates the mental arithmetic error that can occur when
+ managing multiple measurements at once.
+
+
+ Temperature conversion matters in two specific gemmological contexts. First, the
+ specific gravity calculation depends on the density of water at the temperature of
+ the liquid used during hydrostatic weighing: water is densest at 4 °C
+ (1.0000 g/cm³) and becomes measurably less dense as temperature rises,
+ reaching 0.9957 g/cm³ at 30 °C. The SG calculator on the
+ Measurement page applies this water-density correction automatically, and the
+ temperature converter here lets you enter a Fahrenheit reading from a lab thermometer
+ and obtain the Celsius value needed for that correction. Second, some refractometer
+ reference tables and refractive index databases list temperature coefficients in
+ Fahrenheit; converting to Celsius before applying a temperature correction to an RI
+ reading ensures the adjustment is applied in the right direction and magnitude.
+
- Systematic gem identification follows a fixed sequence to avoid confirmation bias.
- Start with non-destructive observations — colour, transparency, lustre — then move
- to refractive index, then specific gravity, then the spectroscope if the RI falls in
- an ambiguous range. Only after these quantitative steps should qualitative tests
- (Chelsea filter, fluorescence) be applied to confirm or refute a working hypothesis.
- This sequence matches the FGA Diploma practical examination protocol, and it matters
- because qualitative tests are sensitive to treatment, coating, and imitation —
- whereas RI and SG are intrinsic physical constants of the material itself.
-
-
- The gem identifier on this page applies this logic directly. Enter the RI reading
- from your refractometer, the SG value from hydrostatic weighing, the crystal system
- if known from polariscope behaviour, and the optic character (singly refractive,
- uniaxial, or biaxial). Each parameter constrains the search independently, and the
- tool returns every family in the 96-entry mineral database that satisfies all the
- criteria you supply simultaneously. You do not need to fill in every field — a single
- RI reading already eliminates the majority of species, and adding SG typically
- reduces the candidate list to three or fewer families. The underlying database
- includes all 93 natural mineral families as well as 13 synthetic, 11 simulant, and
- 4 composite entries, so lookalike materials appear in the same results set as genuine
- natural species.
-
-
- Results are displayed with origin badges that immediately flag whether a matching
- entry is a natural mineral, a lab-grown synthetic with the same chemical composition,
- a simulant made from a different material, or a composite assembled stone. This
- distinction is critical at the identification stage: a stone with an RI of 1.762 and
- SG of 3.99 could be natural ruby, flux-grown synthetic ruby, or a garnet-topped
- doublet — three very different commercial situations that require different follow-up
- tests. Seeing all three in a single ranked results table prevents the common error
- of stopping investigation once a plausible natural species is found.
-
-
- After the identifier narrows the field, the results table provides direct links to
- the relevant entries in the spectroscope band-matcher and UV fluorescence lookup, so
- the next logical test is always one click away. This end-to-end workflow — from
- first observation to a confirmed identification supported by multiple independent
- properties — is the foundation of professional gemmological practice and the
- standard taught at the Gemmological Association of Great Britain.
-
-
+
+
+ About the identifier & methodology
+
+
+
+ Systematic gem identification follows a fixed sequence to avoid confirmation bias.
+ Start with non-destructive observations — colour, transparency, lustre — then move
+ to refractive index, then specific gravity, then the spectroscope if the RI falls in
+ an ambiguous range. Only after these quantitative steps should qualitative tests
+ (Chelsea filter, fluorescence) be applied to confirm or refute a working hypothesis.
+ This sequence matches the FGA Diploma practical examination protocol, and it matters
+ because qualitative tests are sensitive to treatment, coating, and imitation —
+ whereas RI and SG are intrinsic physical constants of the material itself.
+
+
+ The gem identifier on this page applies this logic directly. Enter the RI reading
+ from your refractometer, the SG value from hydrostatic weighing, the crystal system
+ if known from polariscope behaviour, and the optic character (singly refractive,
+ uniaxial, or biaxial). Each parameter constrains the search independently, and the
+ tool returns every family in the 96-entry mineral database that satisfies all the
+ criteria you supply simultaneously. You do not need to fill in every field — a single
+ RI reading already eliminates the majority of species, and adding SG typically
+ reduces the candidate list to three or fewer families. The underlying database
+ includes all 93 natural mineral families as well as 13 synthetic, 11 simulant, and
+ 4 composite entries, so lookalike materials appear in the same results set as genuine
+ natural species.
+
+
+ Results are displayed with origin badges that immediately flag whether a matching
+ entry is a natural mineral, a lab-grown synthetic with the same chemical composition,
+ a simulant made from a different material, or a composite assembled stone. This
+ distinction is critical at the identification stage: a stone with an RI of 1.762 and
+ SG of 3.99 could be natural ruby, flux-grown synthetic ruby, or a garnet-topped
+ doublet — three very different commercial situations that require different follow-up
+ tests. Seeing all three in a single ranked results table prevents the common error
+ of stopping investigation once a plausible natural species is found.
+
+
+ After the identifier narrows the field, the results table provides direct links to
+ the relevant entries in the spectroscope band-matcher and UV fluorescence lookup, so
+ the next logical test is always one click away. This end-to-end workflow — from
+ first observation to a confirmed identification supported by multiple independent
+ properties — is the foundation of professional gemmological practice and the
+ standard taught at the Gemmological Association of Great Britain.
+
- This toolkit covers every quantitative and qualitative test a practising gemmologist needs
- for systematic identification. All calculations run client-side in the browser using the
- same mineral database that powers the mineral reference pages — 96 families including
- natural species, lab-grown synthetics, simulants, and composite stones. No data is
- transmitted to any server; readings stay on your device.
-
-
- The tools are organised across six categories. Measurement & Calculation handles the
- two primary quantitative tests — specific gravity and refractive index — alongside
- birefringence, critical angle, carat estimation, and the Hanneman/Hodgkinson over-the-limit
- shortcut for stones with RI above 1.81. Optical Properties supports the polariscope and
- dichroscope workflow, with a refractometer simulator, pleochroism reasoner, and optic-sign
- determination. Lab Equipment covers spectroscope absorption-band reading, an inverse
- band-matcher for species lookup, and UV fluorescence interpretation. Gem Identification
- provides a filtered database query to narrow candidates by RI, SG, crystal system, and
- optical character. Advanced Analysis integrates treatment-detection evidence weighting and
- GIA cut-grade proportion analysis. Unit Conversions handles metric/troy/decimal-carat and
- temperature scales used in refractometer corrections.
-
-
- The workflow mirrors the FGA Diploma practical examination protocol: start with
- non-destructive observations, then RI, then SG, then spectroscope for ambiguous cases, and
- apply qualitative confirmatory tests last. Each tool includes a brief methodology note so
- students building examination technique can understand not just the result but the reasoning
- behind it.
-
-
+
+
+ About the gemmology toolkit
+
+
+
+ This toolkit covers every quantitative and qualitative test a practising gemmologist needs
+ for systematic identification. All calculations run client-side in the browser using the
+ same mineral database that powers the mineral reference pages — 96 families including
+ natural species, lab-grown synthetics, simulants, and composite stones. No data is
+ transmitted to any server; readings stay on your device.
+
+
+ The tools are organised across six categories. Measurement & Calculation handles the
+ two primary quantitative tests — specific gravity and refractive index — alongside
+ birefringence, critical angle, carat estimation, and the Hanneman/Hodgkinson over-the-limit
+ shortcut for stones with RI above 1.81. Optical Properties supports the polariscope and
+ dichroscope workflow, with a refractometer simulator, pleochroism reasoner, and optic-sign
+ determination. Lab Equipment covers spectroscope absorption-band reading, an inverse
+ band-matcher for species lookup, and UV fluorescence interpretation. Gem Identification
+ provides a filtered database query to narrow candidates by RI, SG, crystal system, and
+ optical character. Advanced Analysis integrates treatment-detection evidence weighting and
+ GIA cut-grade proportion analysis. Unit Conversions handles metric/troy/decimal-carat and
+ temperature scales used in refractometer corrections.
+
+
+ The workflow mirrors the FGA Diploma practical examination protocol: start with
+ non-destructive observations, then RI, then SG, then spectroscope for ambiguous cases, and
+ apply qualitative confirmatory tests last. Each tool includes a brief methodology note so
+ students building examination technique can understand not just the result but the reasoning
+ behind it.
+