Corals are marine organisms that form underwater colonies by secreting a hard, protective exoskeleton. This structure is composed primarily of calcium carbonate, which remains as the material valued for jewelry and decorative pieces after the organism’s life cycle. Because genuine coral is a natural, organic material, it possesses unique characteristics that manufacturers often find difficult to replicate fully. This guide provides simple tests to help authenticate natural coral, distinguishing it from various manufactured or imitation materials currently in the market.
The Importance of Visual Inspection
Determining a coral specimen’s authenticity involves a visual examination of its surface characteristics. Real coral, being an organic growth, rarely exhibits the flawless uniformity often seen in synthetic materials. Under magnification, genuine coral frequently reveals natural growth patterns, which can appear as fine, wood-grain like striations or subtle concentric rings, depending on the species.
Natural coral color is seldom perfectly consistent throughout the entire piece, often displaying subtle variations or banding. Examining the piece with a jeweler’s loupe or a simple magnifying glass may reveal tiny pits, pores, or minute imperfections left by the marine polyps. A surface that appears overly smooth, flawless, or glossy, lacking any of these minute natural textures, should raise immediate suspicion that the piece may be an imitation.
Distinguishing Common Imitations and Fakes
Recognizing the specific signs of common fakes is often the quickest path to verification. Plastic and resin imitations are frequently too lightweight, feeling insubstantial when held, and may display subtle mold lines or a slightly waxy surface texture. Glass simulants, conversely, feel noticeably heavier than genuine coral and may contain tiny air bubbles trapped within the material. Glass also lacks the characteristic organic texture that defines natural coral specimens.
Reconstituted coral is created by mixing pulverized coral powder with plastic resins or binding agents, often resulting in a material that is too uniform in appearance. To check for artificial coloring, inspect any fissures, cracks, or surface pores, as dye tends to concentrate in these areas, making the color appear unnaturally deep. Rubbing a small, hidden area with a cotton swab dipped in acetone may cause color to bleed onto the swab if the coral is dyed.
Simple Physical Tests for Verification
The specimen’s physical interaction with your hand offers tactile clues about its authenticity. Real coral, which is a dense mineral structure, typically feels cool to the touch, similar to natural stone, and warms up very slowly when held in your palm. In contrast, imitations made from plastic or resin often feel warm immediately or quickly absorb body heat.
Coral is relatively light for a mineral-based material, though denser than plastic. If the piece feels unusually heavy, it may be a glass imitation, while an exceptionally light feel suggests a plastic or synthetic resin. Tapping the piece gently against a dense object provides another indication: real coral produces a dull, solid sound, while glass or hard plastic often results in a sharper, higher-pitched clink.
Understanding Real Coral Structure and Composition
The authentication tests rely on coral’s fundamental chemical composition. True coral is formed by marine polyps that extract calcium carbonate from the surrounding seawater to build their skeletons. The most common forms of this mineral in coral skeletons are aragonite or high-magnesium calcite.
This calcium carbonate structure provides the density that makes real coral feel cool and solid to the touch. The biomineralization process also creates the unique, intricate internal structure that gives rise to the wood-grain or striated texture observed under magnification. This organic deposition of calcium carbonate chemically distinguishes it from man-made materials like glass or plastic, whose smooth, homogenous structures lack the natural porosity of coral.