GEMSTONE SPECIES - ORGANIC

Composition --> Organic gem formed by marine invertebrates (Corallium species), comprising a dense calcium carbonate skeleton.
Colour --> Vivid deep red to orangey-red; prized for uniform, intense hues.
Source --> Historically Mediterranean (e.g., Italy, Tunisia); also Pacific varieties (Japan, Taiwan).
Structure --> Solid, fine-grained; polishes to a smooth, glossy finish.
Value Factors --> Color intensity/uniformity, size, lack of surface blemishes, origin (Mediterranean red is often most valued). 

Composition --> Organic gem from calcium carbonate from shallow-water corals.
Colour --> Soft to medium pink, sometimes with peach or salmon tones; uniform coloration is prized.
Sources --> Pacific regions (e.g., Corallium japonicum near Japan) and limited Mediterranean species with lighter hues.
Structure & Hardness --> Fine-grained, polishes to a satin or glossy finish; Mohs hardness 3-4, so fairly soft.
Value Factors --> Evenness of pink colour, absence of spots or streaks, size, and origin (certain Pacific sources favored). 

Composition --> Similar species like other organic gems from the calcium carbonate skeleton of coral polyps, often Corallium
Colour --> Milky white to creamy; sometimes called “angel skin” when showing a soft pinkish overtone.
Sources --> Mediterranean and some Pacific reefs; occasionally from bleached or naturally pale colonies.
Structure --> Fine-grained, polishes to a smooth, satin, or glossy finish
Treatments --> Often bleached or dyed to achieve uniform white; may be stabilized with resin. Disclosure is important. 

Composition --> Skeleton of Heliopora coerulea (blue coral), an aragonite-based coral with iron-derived blue coloration.
Colour --> Natural blue-gray to steely blue; may show silvery sheen.
Source --> Indo-Pacific regions (e.g., Japan, Philippines); often from sustainable or salvaged stocks.
Structure --> fibrous, slightly porous—may require stabilization for jewelry.
Treatments --> Sometimes stabilized (resin) to fill pores; bleaching or dyeing is less common, but disclose if used.

Composition --> Organic skeleton of antipatharian corals, primarily proteinaceous with a chitin-like structure rather than pure calcium carbonate.
Colour --> Deep jet-black to dark brown; may have natural ridges or subtle texture.
Sources --> Harvested from deep-water reefs in the Pacific, Indian, and Atlantic oceans; many species are protected or regulated.
Structure --> Relatively lightweight and durable for organic material
Treatments --> Often polished or waxed to enhance luster; stabilization is rarely needed as structure is less porous.

Composition --> Organic skeleton of certain deep-sea corals (e.g., Tubipora or Isidella), often with segmented, jointed structures.
Colour --> Natural beige to brown or red; sometimes polished to reveal subtle hues.
Structure --> Fairly lightweight and moderately durable for organic material
Treatments --> May be stabilized or lightly polished; any resin filling should be disclosed.

Formation --> Ancient coral skeletons (aragonite) replaced by silica (chalcedony/agate) over millions of years, preserving “flower” or honeycomb patterns.
Composition & Hardness -->  Agatized chalcedony (SiO₂ --> silica); Mohs 6.5–7.
Appearance --> Opaque to translucent; patterns show radial/hexagonal coral structures
Colours --> range white, cream, pink, red, brown, gray, black, depending on impurities.

Sources:
Indonesia --> Vivid, richly patterned material.
USA (Florida, Georgia) --> Subtler tones from ancient reef deposits.
Treatments --> Rarely dyed; occasional stabilization (resin) to fill pits; light waxing for lustre

Value Factors --> Pattern clarity, color contrast, size, provenance; Indonesian material often premiums