Sponge coral is a type of natural coral, not a sponge. Its designation comes from its distinctive porous structure, which bears a resemblance to marine sponges. This unique appearance sets it apart from other corals, making it a recognizable material in various applications. The term helps distinguish it from the more solid, dense corals commonly known in jewelry.
The Nature of Sponge Coral
Sponge coral is a species of coral belonging to the Melithaeidae family, a group of octocorals often referred to as sea fans. Its skeletal structure is composed of calcium carbonate, forming a hard, jointed axis covered by a flexible membrane containing minute calcareous spicules.
The natural formation of sponge coral includes a highly porous, branching network, which gives it a texture reminiscent of a sea sponge. These fan-shaped or bushy colonies naturally inhabit the tropical regions of the Indo-Pacific, with significant populations found in waters around Indonesia and Taiwan.
In its untreated state, sponge coral displays a range of natural colors, typically appearing in shades of red, orange, or reddish-brown. The specific coloration can vary based on the species and environmental conditions of its habitat.
From Ocean to Ornament
Once harvested from the seafloor, sponge coral undergoes specific processing steps to transform it into a durable material suitable for jewelry. Due to its naturally porous and relatively soft composition, the coral is almost always treated to enhance its stability and appearance, making it more resilient for cutting and shaping.
A primary processing method involves stabilization, where the coral is infused with resin. This resin fills the numerous pores and voids within the coral’s structure, significantly increasing its density and hardness. The stabilization process allows the coral to be cut, carved, and polished without crumbling, for creating beads, cabochons, and other jewelry forms.
Sponge coral is frequently dyed to either intensify its natural red or orange tones or to impart entirely different colors. The combination of stabilization and dyeing makes the material more versatile for use in necklaces, bracelets, and earrings.
Caring for Sponge Coral Jewelry
Even after stabilization, sponge coral remains a relatively soft and porous organic material, requiring specific care to maintain its appearance. Proper handling and cleaning methods extend the lifespan of these ornamental pieces.
To clean sponge coral jewelry, gently wipe it with a soft, dry cloth. If a deeper clean is needed, a slightly damp cloth can be used, ensuring it is not overly wet. After cleaning with a damp cloth, immediately dry the piece thoroughly to prevent moisture absorption.
Avoid exposing sponge coral jewelry to harsh chemical cleaners, ultrasonic jewelry cleaners, or steamers, as these can degrade the resin and the coral’s structure. Prolonged soaking in water should also be avoided due to its porous nature. Additionally, keep the jewelry away from perfumes, hairspray, and lotions, as their chemical components can cause damage or discoloration.