Glossary of Pearl Terms J

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Japan Black Pearl Promotion Association: Founded in October 1993, the association promotes cultured pearls from French Polynesia in Japan.

Japanese lingah: Popular name for the Pinctada fucata martensi mollusk.

Japanese pearl mollusk: Akoya pearl mollusk.

Jewelmer: Philippine producer and wholesaler of South Sea pearls, primarily those produced by the gold-lip Pinctada maxima pearl mollusk.

Jin: Historical weight unit used to valuate natural pearls in China during the Ming dynasty (1368-1644 AD). One jin equals 500 grams.

Jiwan: Historical Persian quality factor describing round, pink natural pearls with high luster.

John Guise School of Pearl Culture: Founded in New Guinea by Australian C. Denis George. The school trained villagers in pearl culture.

Jomon Pearl: The world's oldest known pearl, believed to be more than 5,500 years old.

JPEA (Japan Pearl Exporters Association): Founded in 1954, disbanded in 1999 and recently reestablished (with little support), the JPEA is an association of pearl farmers and dealers that works to promote cultured pearls and to ensure that low-grade pearls are not exported from Japan.

JVC (Jewelers Vigilance Committee): US-based nonprofit group that works to ensure legal compliance and ethical standards within the jewelry industry.