Indonesia is a long-standing producer of gemstones across a wide range of categories, with a production profile shaped by the country's complex geology spanning the Sunda Shelf, the volcanic arcs of the Sunda and Banda chains, and the cratonic blocks of Borneo and Sulawesi. The principal Indonesian gem productions are diamonds from Kalimantan (Borneo), South Sea pearls from the eastern archipelago, opal from Banten, and a range of coloured stones including amethyst, rhodonite, chrysoprase and the regional category of "Kalimantan agate" and "Indonesian opalised wood."

Diamonds from Kalimantan

The Cempaka and Martapura districts of South Kalimantan have produced alluvial diamonds for centuries, with documented commercial production dating from the eighteenth century onward. The deposits are placer-type, with diamonds recovered from river gravels rather than from primary kimberlite or lamproite sources, although the source primary rocks are believed to lie within the central Borneo cordillera. Production is artisanal and small-scale (ASM) in character, with traditional pan-and-sluice methods used by independent miners and small cooperatives. Annual production is modest by global standards but supports a regional cutting industry centred on Martapura, where Indonesian-cut diamonds are sold both into the domestic market and to neighbouring Singapore, Malaysia and Thailand for further trade.

The Cempaka diamonds are notable for their typically high colour grade and a tendency toward smaller average crystal sizes, with stones above one carat uncommon. Larger stones, when found, attract premium prices in the local trade and are often retained in Indonesia rather than entering international circulation. Heat-treated and natural pink, brown and yellow fancy-coloured diamonds also appear in Kalimantan production at lower frequencies.

South Sea pearls

Indonesia is one of the world's three principal South Sea pearl-producing countries, alongside Australia and the Philippines. South Sea pearls are produced by the Pinctada maxima oyster (gold-lipped and silver-lipped varieties), and Indonesian production is concentrated in the eastern archipelago, particularly West Papua, Maluku, North Sulawesi and Bali. The Indonesian pearling industry has grown significantly since the 1980s, when serious investment in farm development began, and Indonesia is now the largest producer of golden South Sea pearls, with a particular concentration on the saturated golden colours that are most associated with the country.

Indonesian pearl production runs through both domestic Indonesian companies and joint ventures with Japanese, Australian and other international pearl-trade interests. Quality grading follows the standard South Sea pearl categories of size, shape, surface, lustre, nacre thickness and colour. Indonesian pearls are sold both at the major pearl auctions in Hong Kong and Kobe and through direct trade to international buyers. The country's pearl industry trade body is the Indonesian Pearl Association.

Banten opal and other coloured stones

Indonesia has produced opal from the Banten Province on western Java since the 1970s, with a distinctive variety of common and precious opal locally referred to as "Kalimaya" (a Bantenese term applied to the local opal). The material includes both translucent precious opal with play-of-colour, generally less intense than top-grade Australian or Ethiopian material, and large quantities of common opal in cream, brown and orange body colours used for cabochons and beads.

Other coloured-stone production from Indonesia includes amethyst from Sumatra, chrysoprase from Sulawesi, opalised wood and petrified wood from various localities, rhodonite, and a range of agate, jasper and chalcedony varieties. The Indonesian "Kecubung Rambut" (rutilated quartz) and locality-specific labels for various chalcedony varieties are part of a vibrant domestic trade that overlaps with the wider Southeast Asian coloured-stone market through Bangkok and Chanthaburi.

Sulawesi has produced amber-like fossil resin, marketed as "Sulawesi amber" or "Indonesian amber," though the material is geologically much younger than Baltic amber and is technically a copal in some classifications. Disclosure of this distinction is important in international trade.

The Indonesian gem trade

The Indonesian gem and jewellery trade is concentrated in Jakarta, Surabaya, Bali (particularly the Celuk village area near Ubud, which has long been a centre for silver jewellery production), Yogyakarta and Martapura. Bali silver jewellery, often combining indigenous design traditions with stones from across the archipelago, is one of the most internationally visible categories of Indonesian jewellery and supplies wholesale buyers in Europe, North America and Australia. The major industry trade body is the Asosiasi Pengusaha Permata dan Perhiasan Indonesia.

Hallmarking and standards are governed by the Indonesian National Standardisation Agency through Standar Nasional Indonesia (SNI) provisions covering gold and silver fineness. Domestic enforcement of fineness standards is variable, and international buyers should specify and verify metal quality through their own testing rather than relying solely on stamped marks on Indonesian-made jewellery.