Source Library
The recurring references behind our guides. Listing a source means we cite it, it does not mean any organisation endorses us, or that we endorse it.
Public bodies
National Gem and Jewellery Authority of Sri Lanka (NGJA)
The Sri Lankan state regulator for the gem and jewellery industry, including dealer licensing and export-related services.
Used for: Licensing, export procedure and regulatory references. Always verify current rules directly.
Accessed 2026-07-25 · Verified by the editorial team
The government agency responsible for customs control at Sri Lankan borders.
Used for: Customs declaration and traveller allowance references. Always verify current rules directly.
Accessed 2026-07-25 · Verified by the editorial team
Sri Lanka’s central bank, publishing exchange rates and economic data.
Used for: Currency and economic context for indicative price information.
Accessed 2026-07-25 · Verified by the editorial team
Import and Export Control Department of Sri Lanka
The Sri Lankan department administering import and export licensing and control regulations.
Used for: Import/export licensing regime references. Always verify current rules directly.
Accessed 2026-07-25 · Verified by the editorial team
Geological Survey and Mines Bureau (GSMB)
Sri Lanka’s geological survey and mining regulator.
Used for: Mining licensing context only. The GSMB website blocks automated access, so its pages are search-confirmed only; no GSMB content is quoted on this platform until verified manually.
Title and URL confirmed via search only; not quoted for content
Official documents and guidance
“Licences - NGJA” · National Gem and Jewellery Authority of Sri Lanka
The NGJA’s official overview of licence types, including gem dealer licences, lapidary licences, mining licence processes, jewellery industrialist registration and online export licences.
Used for: Statements about which licence types exist and that dealing/export requires NGJA licensing.
Accessed 2026-07-25 · Verified by the editorial team
“Gem Testing Laboratory - NGJA” · National Gem and Jewellery Authority of Sri Lanka
The NGJA’s page on its gem testing and valuation services, certificates and testing centres, including online certificate verification.
Used for: Statements that the Sri Lankan state operates a gem testing laboratory and issues verifiable certificates.
Accessed 2026-07-25 · Verified by the editorial team
NGJA: Gem & Jewellery Export Process
“Gem & Jewellery Export Process - NGJA” · National Gem and Jewellery Authority of Sri Lanka
The NGJA’s official description of the gem and jewellery export procedure, including examination by gemmologists and customs officers, fee structure and export centres in Colombo, Ratnapura and Katunayake.
Used for: Export-procedure statements in the Rules & Export section.
Accessed 2026-07-25 · Verified by the editorial team
“Travellers – Sri Lanka Customs” · Sri Lanka Customs
The official passenger guidance covering declaration duties on arrival and departure, including foreign currency, gold jewellery and gems, baggage rules and penalties for false declaration.
Used for: Traveller declaration statements in the Rules & Export section.
Accessed 2026-07-25 · Verified by the editorial team
“Exchange Rates” · Central Bank of Sri Lanka
The Central Bank’s official exchange-rate publication, including LKR rates against major currencies and gold price data.
Used for: Statements that official LKR exchange rates and gold price data are published by the Central Bank; candidate source for a future documented gold price methodology.
Accessed 2026-07-25 · Verified by the editorial team
British Hallmarking Council: Guidance on Fineness
“Guidance on Fineness Description” · British Hallmarking Council · April 2014
Official UK guidance linking fineness numbers to carat descriptions, including 916/22ct, 750/18ct and 585/14ct.
Used for: Karat-to-fineness equivalence statements (916 = 22K, 750 = 18K, 585 = 14K).
Accessed 2026-07-25 · Verified by the editorial team
Assay Offices of Great Britain: Hallmarking Guidance Notes
“Hallmarking Guidance Notes” · Assay Offices of Great Britain · November 2022
Guidance notes on UK hallmarking, listing recognised precious-metal fineness standards including gold 916.6.
Used for: Statements on recognised gold fineness standards and hallmarking practice in a regulated regime.
Accessed 2026-07-25 · Verified by the editorial team
Standards organisations
CIBJO, The World Jewellery Confederation
International confederation publishing the CIBJO Blue Books, widely used standards for gemstone and precious-metal nomenclature and disclosure.
Used for: Terminology, treatment disclosure standards and trade definitions.
Accessed 2026-07-25 · Verified by the editorial team
International Colored Gemstone Association (ICA)
An international trade association for the coloured-gemstone industry.
Used for: General coloured-gemstone trade context.
“The Blue Books - CIBJO” · CIBJO, The World Jewellery Confederation
The download and overview page for the CIBJO Blue Books: grading standards and nomenclature for diamonds, coloured gemstones, pearls, coral, precious metals, gemmological laboratories and responsible sourcing, reviewed annually.
Used for: Treatment disclosure and nomenclature standard statements.
Accessed 2026-07-25 · Verified by the editorial team
Gemological laboratories
Gemological Institute of America (GIA)
A major international gemological research and education institute and laboratory.
Used for: Published gemological reference values and grading concepts. Reference only, no affiliation.
Accessed 2026-07-25 · Verified by the editorial team
SSEF, Swiss Gemmological Institute
A Swiss laboratory known for coloured-gemstone origin and treatment reports.
Used for: Origin-report and treatment-report concepts. Reference only, no affiliation.
Accessed 2026-07-25 · Verified by the editorial team
A Swiss gemmological laboratory specialising in coloured gemstones.
Used for: Origin-report and treatment-report concepts. Reference only, no affiliation.
A Bangkok gemmological laboratory specialising in ruby and sapphire, publishing a substantial research article library.
Used for: Corundum treatment detection research and sapphire terminology. Reference only, no affiliation.
Accessed 2026-07-25 · Verified by the editorial team
“Sapphire - SSEF” · SSEF Swiss Gemmological Institute
SSEF’s page on sapphire testing, covering origin determination through microscopic features, trace-element chemistry and spectroscopy against reference collections, and treatment disclosure practice.
Used for: Origin-determination methodology and royal blue terminology statements.
Accessed 2026-07-25 · Verified by the editorial team
Journal articles and research
Gems & Gemology (Fall 2014): Sri Lanka expedition
“Sri Lanka: Expedition to the Island of Jewels” · Gems & Gemology (GIA), Fall 2014, Vol. 50, No. 3 · Andrew Lucas, Armil Sammoon, A. P. Jayarajah, Tao Hsu, Pedro Padua · Fall 2014
A field report covering the Sri Lankan gem industry from mining to market, including the heat treatment of geuda sapphire.
Used for: Geuda and heat-treatment history statements; mine-to-market industry structure.
Accessed 2026-07-25 · Verified by the editorial team
Lotus Gemology: Low-temperature heat treatment experiments
“Madagascar Sapphire, Low-Temperature Heat Treatment Experiments” · Lotus Gemology · E. Billie Hughes, Rosey Perkins · 2019
Systematic heating experiments on sapphire between 800°C and 1500°C, documenting detection evidence such as inclusion changes and chalky short-wave UV fluorescence.
Used for: Statements about how laboratories detect heat treatment and the limits of detection at low temperatures.
Accessed 2026-07-25 · Verified by the editorial team
Lotus Gemology: Padparadscha essay
“Padparadscha Sapphire & the Ownership of Words” · Lotus Gemology · Richard W. Hughes · 2005
An essay on the definition and etymology of padparadscha sapphire, discussing the LMHC definition of light-to-medium pinkish orange to orange-pink hues.
Used for: Padparadscha definition, etymology and the definitional debate.
Accessed 2026-07-25 · Verified by the editorial team
Educational references
Gem-A, The Gemmological Association of Great Britain
The world’s oldest provider of gemmological education (established 1908), publisher of The Journal of Gemmology.
Used for: Gemmological education standards and terminology.
Accessed 2026-07-25 · Verified by the editorial team
“Sapphire Description” · Gemological Institute of America
GIA’s reference description of sapphire: corundum variety, colour range and colour causes, with Sri Lanka named among traditional sources.
Used for: Sapphire identity and colour-cause statements.
Accessed 2026-07-25 · Verified by the editorial team
GIA: Sapphire Care and Cleaning Guide
“Sapphire Care and Cleaning Guide” · Gemological Institute of America
GIA’s guidance on sapphire hardness, toughness and how treatments affect care and cleaning.
Used for: Hardness (Mohs 9), durability and treatment-dependent care statements.
Accessed 2026-07-25 · Verified by the editorial team
“Sapphire Quality Factors | Different Types & Colors of Sapphire | GIA” · Gemological Institute of America
GIA’s explanation of quality factors for sapphire, including colour as the dominant value factor and padparadscha among fancy sapphires.
Used for: Sapphire value-factor statements and padparadscha classification.
Accessed 2026-07-25 · Verified by the editorial team
IGS: Sapphire value and information
“Sapphire Value, Price, and Jewelry Information - Gem Society” · International Gem Society
Consumer-level reference on sapphire value factors, treatments, synthetics and origin premiums.
Used for: Consumer-level value-factor statements.
Accessed 2026-07-25 · Verified by the editorial team
“Diamond Carat Weight | Understanding Carat Measurement | GIA 4Cs” · Gemological Institute of America
GIA’s definition of the metric carat.
Used for: The definition that one metric carat equals 200 milligrams (0.2 grams).
Accessed 2026-07-25 · Verified by the editorial team
Goldsmiths’ Company Assay Office: UK Hallmarks
“What is a Hallmark?” · The Goldsmiths’ Company Assay Office, London
The London Assay Office’s explanation of hallmarks and recognised finenesses.
Used for: Hallmark concept statements in a long-established hallmarking regime.
Accessed 2026-07-25 · Verified by the editorial team
References
A widely used public mineralogical database.
Used for: Mineralogical data such as crystal systems and localities.
Accessed 2026-07-25 · Verified by the editorial team
International Gem Society (IGS)
A long-running public gemology education resource.
Used for: General gemological education references.
Accessed 2026-07-25 · Verified by the editorial team
“Corundum (mindat.org mineral page)” · Mindat.org
The Mindat mineral page for corundum (α-Al₂O₃), the Mohs hardness reference species for hardness 9.
Used for: Corundum mineralogical data.
Accessed 2026-07-25 · Verified by the editorial team
“Chrysoberyl: Mineral information, data and localities.” · Mindat.org
The Mindat mineral page for chrysoberyl.
Used for: Chrysoberyl mineral data once verified by direct access.
Title and URL confirmed via search only; not quoted for content