The pattern of wavelengths of light absorbed by a gemstone, recorded using a spectroscope. Natural chromium-coloured jadeite typically shows absorption lines at approximately 630, 660, and 690 nm in the red region, and an iron absorption band at approximately 437 nm in the blue region.

Web-like surface fractures caused by acid treatment in Type B jadeite. These patterns are distinct from the natural orange peel effect and are a diagnostic indicator of chemical treatment. Under magnification, acid etching appears as sharp, irregular networks that disrupt the surface continuity, whereas untreated jadeite shows smooth, organic undulation.

Describes a material whose optical properties vary with direction. Jadeite, as a polycrystalline aggregate, is anisotropic. Under a polariscope, it remains light through a full 360 degree rotation, which is a key identification characteristic.

A solid, circular jadeite form worn as a bracelet. Dimensions are recorded on certificates as outer diameter x inner diameter x width. The cut is typically polished smoothly to follow the wrist contour.

The cleanliness and fineness of the jadeite matrix — the parts of the stone beyond its colour. A strong base is clear, fine-grained, and free from cloudiness, heavy cotton formations, or distracting inclusions. It is what allows colour and water to express themselves fully. A poor base undermines everything above it.

A spherical or near-spherical jadeite form, commonly strung for necklaces or bracelets. Weight is recorded per bead or as total strand weight.

Opaque to slightly translucent jadeite with visible crystal grain. The name derives from the bean-like appearance of the crystal structure. While less translucent than Ice Type or Glutinous Type, Bean Type can still possess attractive colour and is commonly used in carved forms and accessible jewellery.

The liveliness and tonal freshness of colour — how vivid and alive the green appears. Brightness is what separates a flat, dull green from one that glows with internal light. In traditional colour evaluation, brightness works together with purity, richness, and evenness to determine overall colour quality. A stone may be pure and rich in hue but lack brightness if the tone is too dark or dull.

A carved jadeite form depicting a seated or standing Buddha figure. Dimensions follow the standard length x width x thickness format. Cut refers to the surface finish and polishing of carved planes.

A jadeite cut with a domed, polished top and flat base. Designed to enhance light return, colour depth, and translucency. Recorded on certificates alongside terms such as oval shape cabochon or marquise shape cabochon.

A supplementary testing tool that transmits only deep red and yellow-green wavelengths. Used in jadeite testing to assist in detecting artificial dye. Natural chromium-coloured jadeite typically shows little to no reaction. A pronounced red or orange reaction may suggest artificial dye.

An element or compound responsible for producing colour in a gemstone. The primary chromophores in jadeite are iron (Fe3+) and chromium (Cr3+).

Describes how colour is arranged across a stone. Recorded on certificates as even, uneven, patches, veins, or spots. Uneven distribution is common and does not indicate treatment; value follows the quality and placement of colour zones.

The standardised GAHK terminology for expressing the combined saturation and tone of a jadeite colour. The prefix terms are pale, light, bright, intense, deep, and dark. Assessed under daylight-equivalent reflected light.

White, cloud-like inclusions within jadeite that resemble cotton fibres or mist. Light cotton is natural and common; heavy cotton can reduce translucency and visual clarity. Cotton is distinct from cracks and stone lines, and is one manifestation of jadeite's structural fingerprint (翠性). In evaluation, the question is whether cotton distracts from or contributes to the stone's character.

Fractures in the stone that can affect durability and value. Cracks are distinct from stone lines (natural growth patterns) and are generally undesirable, especially if they are surface-reaching or compromise structural integrity. In certificate language, cracks may be recorded as "fractures" or "fissures," and their presence can affect treatment assessment.

The harmonious distribution of colour across the stone. Evenness does not require uniformity; it requires that colour placement feels intentional and balanced rather than chaotic or poorly positioned. A stone with uneven colour can still be beautiful if the colour sits prominently and moves harmoniously through the form. In traditional evaluation, 均 is one of the four classical colour standards.

The formal gemmological family name covering three related pyroxene-group minerals: Jadeite Jade (NaAlSi2O6), Omphacite Jade [(Ca,Na)(Mg,Al)Si2O6], and Kosmochlor Jade (NaCrSi2O6). In commercial use, "Fei Cui" and "jadeite" are often used interchangeably, but gemmologically they are distinct. SÈVE works exclusively with Jadeite Jade.

A decorative pattern where colour appears to float within translucent jadeite, creating a soft, cloud-like or misty effect. Floating flowers are highly prized when the colour is vivid, the pattern is harmonious, and the translucency allows the "flowers" to appear suspended within the stone. This phenomenon is most visible in Ice Type and High Ice Type material.

The emission of visible light by a substance when excited by ultraviolet radiation. Natural jadeite typically shows none to faint fluorescence. A strong response may indicate resin impregnation.

The instrument used in Standard Test Method 13 to detect resin impregnation. It records the infrared absorption profile of the stone; resin-impregnated material produces characteristic peaks absent in natural Type A jadeite. It is also used to distinguish between the three Fei Cui members by their molecular vibration fingerprints.

Founded in 1979 and incorporated in 1998, GAHK is Hong Kong's leading professional gemmological body. It promotes industry professionalism, disseminates gemmological research, and established the Standard Methods for Testing Fei Cui for Hong Kong (2016), the testing standard under which HKJSL issues its certificates.

A translucency quality in which light appears to move through a substance with softness and body, rather than full transparency. Most associated with Ice Type and Glutinous Type material: fine enough in grain to produce interior depth, but with sufficient internal structure to give the light body rather than full transparency. Not a laboratory classification; assessed by eye and described impressionistically.

The highest grade of translucency, where the stone appears almost as clear as glass with exceptional luminosity. Glass Type jadeite exhibits internal luminescence (起螢) and represents the pinnacle of water and texture. The crystal structure is so fine and compact that light passes through with minimal scattering, creating a sense of depth and quiet glow. This is exceptionally rare material.

Semi-translucent jadeite with a soft, rice-like or sticky-rice appearance. The grain is visible but fine, creating a warm, tactile quality rather than the clarity of Ice Type. Glutinous Type jadeite often exhibits gelatinous depth (起膠), where light appears to move through a soft, viscous body. This type is valued for its gentle, approachable character and is commonly used in carved forms and everyday jewellery.

A grade between Ice Type and Glass Type, with exceptional translucency and a soft, glowing quality. High Ice Type material often shows internal luminescence (起螢) and has a crystal structure fine enough to create significant light penetration while maintaining optical depth. It is highly prized for its balance of clarity and character.

Founded in 1993 by the Hong Kong Jewellery & Jade Manufacturers Association, HKJSL is Hong Kong's most established jade testing institution. Equipped with advanced infrared spectrometry and staffed by gemmologists trained exclusively in Fei Cui identification, its certificates are recognised by leading international auction houses. SÈVE certifies all pieces through HKJSL.

The basic colour impression of a stone. For green Fei Cui, the standard hue terms under the Standard Methods are yellowish green, green, and bluish green.

Highly translucent jadeite with a clear, icy appearance. The grain is fine enough to allow significant light penetration, though not as transparent as Glass Type. Ice Type often exhibits gelatinous depth (起膠) and is valued for its balance of translucency and structural character. It is one of the most sought-after types in the fine jadeite market.

An informal trade term for the most prized colour in jadeite: vivid, intense green with strong chromium-driven saturation and good translucency. Not a formally defined gemmological grade, but widely recognised in the Hong Kong and Chinese jadeite market.

A soft, floating luminescence that appears to hover just above or within highly translucent jadeite. Caused by light scattering through a crystal structure of exceptional fineness. Observed almost exclusively in Glass Type and High Ice Type material. Not to be confused with UV fluorescence.

A sodium aluminium silicate mineral (NaAlSi2O6) of the pyroxene group. Forms as a polycrystalline aggregate. Mohs hardness: 6.5-7. Specific gravity: 3.25-3.50, with fine-quality material typically clustering around 3.30-3.36. Refractive index: 1.65-1.67 (+/-0.01), conventionally cited as approximately 1.66. The most commercially prized member of the Fei Cui family.

The chromium-rich end-member of the jadeite-kosmochlor solid solution series. As chromium content in jadeite increases, the mineral composition shifts progressively toward kosmochlor. Very dark green to black material that is predominantly kosmochlor is classified separately as Kosmochlor Jade under the GAHK standard, distinct from Jadeite Jade.

A scale from 1, the softest, to 10, the hardest, rating a mineral's resistance to scratching. Jadeite rates 6.5-7. Hardness is distinct from toughness; jadeite's exceptional resistance to breaking and chipping comes from its polycrystalline structure, not its hardness rating alone.

A calcium magnesium silicate mineral; one of the two gemstones commonly referred to as "jade". Softer and more widely distributed than jadeite, nephrite was the dominant jade in Chinese material culture prior to the 18^th century. The two minerals are chemically, gemmologically, and commercially distinct.

A trade term for jadeite from primary bedrock deposits, meaning less weathered and more abundant material. Often, but not always, associated with coarser texture or lower translucency. Exceptional material emerges from both deposit types.

A pyroxene-group mineral and one of the three formal members of the Fei Cui family. Refractive index: 1.67-1.68, normally read as 1.67. Specific gravity: 3.30-3.45. Distinguished from Jadeite Jade by its distinct molecular composition and spectroscopic fingerprint.

A trade term for jadeite from secondary alluvial deposits, meaning material naturally weathered, transported by water, and sorted over time. Often associated with fine grain structure and high translucency, but not a laboratory classification and not a guarantee of quality.

A surface texture visible under magnification, resembling the skin of an orange. Caused by anisotropic hardness: crystals at different orientations resist polishing at different rates. In natural Type A jadeite, undulations are smooth and organic. In treated Type B jadeite, acid impregnation produces sharp, web-like fracture patterns.

An instrument that passes polarised light through a gemstone to determine its optical nature. Natural jadeite, as a polycrystalline aggregate, remains light through a full 360 degree rotation, confirming it is anisotropic and polycrystalline.

Composed of many interlocking crystals rather than a single crystal. Jadeite's polycrystalline structure is responsible for its toughness and its characteristic behaviour under a polariscope.

The hue must be a pure, uncontaminated green — free from grey, brown, yellow, or blue deviation. In traditional evaluation, this is called 邪 (xié): a "deviant" green that has been pulled off-axis by unwanted undertones. Purity is the first test of colour quality. A pure green may still vary in saturation, tone, and distribution, but it must read as true green without muddiness or colour contamination. Without purity, other colour qualities are compromised.

The ratio of the speed of light in vacuum to the speed of light in the gemstone. Measured using a refractometer by the spot reading method. Jadeite Jade: 1.65-1.67 (+/-0.01), conventionally cited as approximately 1.66. A reading outside this range may indicate a different mineral or a simulant.

The depth and saturation of colour — how full and concentrated the green appears. A stone may be pure in hue but too pale to possess richness. Richness must be considered together with tone and translucency: a deeply saturated stone that is too dark may appear dense rather than luminous. In traditional evaluation, richness (濃) is one of the four classical colour standards.

A flat, circular jadeite form, often used for pendants or decorative plaques. Dimensions follow length x width x thickness.

An elongated, slightly curved plaque form, commonly used for rings or pendants. Cut follows the natural contour of the stone to maximise colour and translucency.

The strength, purity, or intensity of a colour. In the GAHK system, saturation is assessed together with tone to produce the colour prefix.

The density of a gemstone relative to water, determined by hydrostatic weighing. Jadeite Jade: 3.25-3.50, with fine-quality material typically clustering around 3.30-3.36. Not applicable for mounted pieces.

The official testing standard published by The Gemmological Association of Hong Kong Limited (GAHK) on 19 February 2016. It defines thirteen standard methods for identifying and classifying Fei Cui, including optical, physical, and spectroscopic tests, and forms the basis of all HKJSL Standard Certificates.

Natural growth lines or internal patterns formed during the stone's geological creation. Unlike cracks, stone lines do not compromise structural integrity and are often considered part of the stone's natural character. In certificate language, they may be recorded as "natural inclusions" or "growth patterns." Stone lines are distinct from treatment-related features and do not affect Type A status.

A faint shimmer or flash visible on the surface of jadeite, produced by light reflecting off exposed crystal cleavage planes. A diagnostic characteristic of jadeite, most visible in coarser-grained material. It has three manifestations: fly's wing, orange peel effect, and cottony inclusions.

The holistic trade concept encompassing jadeite's internal grain structure, the tightness of its crystal arrangement, and the resulting optical quality, primarily its capacity to transmit light. Evaluated on a spectrum from glass type through ice type and glutinous type to bean type. Not a laboratory classification; assessed by eye and described impressionistically.

The arrangement and grain size of the interlocking crystals in jadeite. Classified in four grades: very fine grain, fine grain, medium grain, and coarse grain. Texture is the structural foundation that determines a stone's capacity to transmit light.

The relative lightness or darkness of a colour. Combined with saturation to determine the colour prefix in the GAHK system.

The degree to which light passes through a stone, formally classified by GAHK as transparent, translucent, or opaque. Assessed under bright transmitted light.

The trade term for the depth and quality of light transmission through jadeite. Described on a three-point scale based on approximate light penetration depth: about 3 mm, 6 mm, and 9 mm or more. A direct expression of grain fineness and crystal interlocking.

The four classification categories for jadeite based on treatment status: Type A, natural and untreated; Type B, chemically treated and resin impregnated; Type C, dyed; and Type B+C, chemically treated, resin impregnated, and dyed. Only Type A is considered natural and untreated.

Natural, untreated jadeite. It has not been subjected to any form of chemical treatment, resin impregnation, or dyeing. Surface wax polishing is not classified as a chemical treatment and does not affect Type A status. All SÈVE pieces are Type A.

Jadeite that has been chemically bleached to remove unwanted colouration and then impregnated with polymer resin to improve stability and appearance. Type B jadeite is not considered natural in the fine jadeite market and is significantly less valuable than Type A. Under magnification, Type B material may show acid etching patterns and a duller surface lustre. FTIR testing can detect resin impregnation definitively.

Jadeite that has been both chemically bleached, resin impregnated, and dyed. This represents the most extensive treatment and is not considered natural. Type B+C material combines the structural alteration of Type B with artificial colouration, making it the least desirable category in the fine jadeite market.

Jadeite that has been artificially coloured through dyeing. The colour is not natural and may fade over time or under exposure to heat and light. Type C jadeite is not considered natural. Under magnification, dye may concentrate along cracks and grain boundaries, creating a web-like colour distribution that differs from natural colour placement.

The standard finishing process for natural jadeite. A thin application of colourless wax is used to enhance surface lustre. Under the GAHK standard, wax polishing is not classified as a chemical treatment and does not affect Type A status.