The Gem-A practical kit is a curated collection of gemstone specimens and testing materials issued to students enrolled in the Gemmological Association of Great Britain's (Gem-A) Diploma programme. Designed to support preparation for the Fellowship of the Gemmological Association (FGA) practical examination, the kit brings together representative examples of major gem species, simulants, and synthetic materials, giving candidates hands-on familiarity with the range of stones and diagnostic features they will encounter under examination conditions.

Purpose and Context

The FGA qualification is widely regarded as one of the most rigorous gemmological credentials available, and its practical examination component is a formal requirement alongside the written theory papers. Where the theory papers assess a candidate's knowledge of crystal systems, optical properties, chemical compositions, and gem identification principles, the practical examination demands that this knowledge be applied swiftly and accurately to actual stones using standard gemmological instruments. The practical kit bridges the gap between theoretical study and applied competence, allowing students to rehearse identification routines repeatedly before sitting the examination.

Contents

The precise composition of the kit is periodically reviewed by Gem-A, but it typically includes:

• Faceted and cabochon specimens representing major gem species — including corundum (ruby and sapphire), beryl (emerald and aquamarine), chrysoberyl, tourmaline, topaz, quartz varieties, garnet group members, and feldspar group stones, among others.
• Common simulants, such as glass and assembled stones (doublets and triplets), which students must distinguish from natural counterparts.
• Synthetic materials produced by recognised growth methods — flame-fusion (Verneuil) corundum and spinel, hydrothermal synthetics, and flux-grown stones — so that candidates can practise identifying the characteristic inclusions and optical signatures that differentiate them from natural gems.

Instruments and Techniques Tested

The practical examination evaluates proficiency across the principal instruments of the gemmological laboratory. Students are expected to demonstrate competent use of:

• Refractometry — measuring refractive index and birefringence, and interpreting shadow-edge readings for singly and doubly refractive stones.
• Polariscopy — distinguishing isotropic from anisotropic materials, and identifying anomalous double refraction in glass and garnets.
• Spectroscopy — reading absorption spectra with a hand spectroscope or desk spectroscope to identify diagnostic bands (the chromium doublet in ruby, the 450 nm band in blue sapphire, the didymium bands in certain glasses, and so forth).
• Microscopy — examining inclusions, growth structures, gas bubbles, curved striae in flame-fusion synthetics, and other internal features under the gemmological microscope.

Candidates are also expected to make use of the Chelsea colour filter, ultraviolet lamps, and the polarising filter where appropriate, and to record their observations systematically before arriving at a confident identification.

Role in Examination Preparation

Because the FGA practical examination is conducted under timed conditions with unfamiliar stones, repeated handling of the kit specimens is considered essential preparation. Working through the collection trains the eye to recognise characteristic colours and lustre, acclimatises the hand to efficient instrument technique, and builds the pattern-recognition that experienced gemmologists rely upon. Students are encouraged to approach each stone methodically — recording specific gravity estimates, refractive index readings, optic character, and any notable inclusions — mirroring the systematic workflow expected in the examination itself.

The kit also serves a subtler purpose: it demonstrates the breadth of variation within a single species. A student who has handled multiple sapphire specimens of differing colour, clarity, and geographic origin is better prepared to avoid misidentification than one who has encountered only textbook descriptions. Similarly, exposure to convincing simulants and well-made synthetics sharpens the critical eye in ways that written study alone cannot replicate.

Further Reading

• Gem-A — FGA Qualification Overview