Hawaii black coral is an organic gemstone material derived from the skeletal remains of deep-water antipatharian corals (Antipathes spp.) found in the submarine waters surrounding the Hawaiian archipelago. Designated the official state gemstone of Hawaii in 1987, it holds a unique position in the American gem trade as both a culturally significant material and a tightly regulated natural resource. The dense, resinous skeleton polishes to a rich, near-metallic lustre and has been fashioned into jewellery, carved figurines, and ornamental objects for well over a century. Its combination of rarity, deep colour, and conservation complexity makes it one of the most carefully governed organic gem materials in the world.

Book a private viewing in Toronto, Canada and hold our pearls in your hand.

Biological and Physical Character

Antipatharian corals — commonly called black corals or thorny corals — are colonial cnidarians belonging to the order Antipatharia. Unlike the calcium-carbonate skeletons of reef-building stony corals, antipatharians produce a proteinaceous, chitin-like skeleton that is naturally dark brown to jet black. The colour arises from melanin-like pigments embedded within the organic matrix; freshly harvested material is often covered in a thin layer of living polyps and tissue that must be removed before the underlying skeleton is revealed in its characteristic dark hue.

The physical properties of black coral are modest by mineralogical standards but entirely appropriate for an organic gem:

• Hardness: approximately 3 to 4 on the Mohs scale — harder than amber or jet, but softer than most mineral gems
• Lustre: resinous to sub-vitreous when polished, capable of a high mirror-like finish
• Specific gravity: approximately 1.34 to 1.46, varying with the density of the individual colony
• Refractive index: approximately 1.56 to 1.57 (singly refractive, isotropic)
• Colour: dark brown to jet black; occasional specimens show a warm golden-brown tone in thin cross-section under transmitted light

The skeletal structure is composed of concentric growth rings, visible in cross-section, which gemmologists and marine biologists alike use to estimate colony age. Growth rates are exceptionally slow — on the order of a few centimetres per year — meaning that large, commercially harvestable colonies may be several hundred years old. This biological reality underpins the entire regulatory framework governing the trade.

Explore our pearl collection — hand-selected and GIA-certified, in Toronto, Canada.

Hawaiian Waters and Habitat

The principal harvesting grounds lie in the deep waters off the islands of Maui and the island of Hawaii (the Big Island), particularly in the Au'au Channel between Maui and Lana'i, where dense antipatharian thickets have been documented at depths ranging from roughly 30 metres to well beyond 100 metres. The most commercially significant beds are found between approximately 30 and 90 metres — accessible to trained divers using surface-supplied or mixed-gas equipment, but deep enough to have remained largely undisturbed by recreational diving or anchor damage.

Hawaii's warm, nutrient-rich waters support some of the most extensive black coral communities in the Pacific. The colonies grow on hard substrate along submarine ridges and slopes, sometimes forming tree-like structures exceeding two metres in height. Their slow growth and the physical inaccessibility of deep-water habitat mean that recovery from over-harvesting is measured in generations rather than years.

Harvesting and Regulation

Commercial harvesting of Hawaiian black coral is governed by an interlocking framework of state and federal regulations, supplemented by international treaty obligations. The Hawaii Division of Aquatic Resources (DAR) issues limited commercial harvesting permits and sets annual quotas based on stock assessments. Harvesters are required to leave a minimum percentage of each colony intact to allow regeneration, and certain depth zones and geographic areas are designated as protected refugia entirely closed to harvest.

At the international level, black coral is listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which requires that any export be accompanied by documentation confirming legal and sustainable origin. This listing does not prohibit trade but subjects it to a permitting system designed to prevent unsustainable exploitation. Dealers and jewellers operating in the Hawaiian market are required to maintain chain-of-custody records, and the sale of undocumented black coral — or of coral harvested outside permitted quotas — is a criminal offence under both state and federal law.

The commercial harvest is conducted almost exclusively by a small number of licensed professional divers, many of whom have operated in Hawaiian waters for decades. The community is tight-knit, and the practical knowledge of productive grounds and sustainable harvesting technique is passed between experienced practitioners. This artisanal character distinguishes Hawaiian black coral from the industrialised harvesting that has depleted antipatharian populations in other parts of the world.

Working and Jewellery Applications

Raw black coral branches are cut, shaped, and polished using lapidary equipment broadly similar to that used for other organic gem materials. The material carves readily with rotary tools and responds well to progressive grits of abrasive paper, finishing to a high gloss with polishing compounds. Because the skeleton is composed of concentric fibrous layers, skilled craftspeople can exploit the grain to produce cabochons, beads, and carved forms that display the natural texture of the material.

Hawaiian black coral is most commonly set in yellow gold — a combination that has become strongly associated with traditional Hawaiian jewellery design. The contrast between the warm metal and the deep, lustrous black of the coral is visually striking and has been a hallmark of Maui-based jewellers since at least the mid-twentieth century. Contemporary designers also work the material into sculptural pendants, earrings, and cuff links, sometimes combining it with pearl, shell, or coloured gemstones in compositions that reference the broader visual culture of the Pacific.

Carved figural pieces — depicting marine life, Hawaiian cultural motifs, and abstract forms — represent a distinct tradition within the trade and command premium prices when executed with skill. The finest carved specimens, particularly those incorporating large, unbranched sections of trunk material, are treated by serious collectors as objets d'art rather than merely as jewellery components.

Identification and Imitation

Genuine black coral can be distinguished from common imitations — dyed glass, black plastic, and vulcanite — by a combination of its relatively low specific gravity, its warm feel (organic materials are poor thermal conductors compared to glass), and its characteristic fibrous structure visible under magnification. A hot-point test, applied only to an inconspicuous area, will produce a faint organic odour from genuine coral but a sharp chemical smell from most plastics. Gemmological laboratories can confirm identification through infrared spectroscopy, which produces a characteristic absorption pattern consistent with the proteinaceous organic matrix.

Jet, another black organic gem, is sometimes confused with black coral in the secondary market, but jet is fossilised wood and displays a distinctly different internal structure and a slightly higher hardness. Dyed freshwater pearl and black chalcedony are occasionally encountered as substitutes in lower-price-point jewellery but are readily distinguished by their physical properties.

Cultural and Historical Significance

Black coral has been used ornamentally in Hawaii since at least the nineteenth century, and its designation as the state gemstone reflects a recognition of its deep association with Hawaiian identity and the marine environment. In broader Pacific cultures, coral in various forms has carried spiritual and protective significance, and antipatharian coral is referenced in several Polynesian traditions as a material of power and prestige.

The commercial jewellery trade in Hawaiian black coral expanded significantly during the mid-twentieth century as tourism to the islands grew and demand for distinctive local gem materials increased. The industry's subsequent contraction — driven by tightening regulation and the depletion of accessible shallow-water colonies — has, paradoxically, enhanced the material's desirability and value. Pieces documented as pre-regulation or accompanied by full provenance and CITES paperwork are increasingly sought by collectors who understand the material's conservation history.

Conservation Outlook

The long-term sustainability of Hawaiian black coral as a gem material depends entirely on the continued rigorous enforcement of existing harvest limits and the health of deep-water marine ecosystems. Climate change, ocean acidification, and the indirect effects of deepwater fishing activities all pose background threats to antipatharian communities, though the deep-water habitat of Hawaiian black coral affords it some degree of insulation from the bleaching events that have devastated shallow reef systems elsewhere. Marine biologists continue to monitor colony density and recruitment rates in key harvesting areas, and the regulatory framework is subject to periodic review as new stock assessment data become available.

Pick a pearl and let us create your bespoke jewellery — designed and made in Toronto, Canada since 1967.

Further Reading

• GIA: Black Coral
• AGTA: Black Coral Gemstone Information
• IGS: Black Coral Jewelry and Gemstone Information