The legendary scent of ambergris - which has been all but lost to perfume lovers - has been recovered from a specimen held in a Tokyo museum and will be released at an upcoming exhibition to mark the International Year of Biodiversity.

Ambergris, which takes its name from a combination of "amber" and "gris," the French word for grey, is one of the most precious naturally occurring fragrance materials in the world. Physically, it is a lumpy, oily material that comes in unpromising shades of blacks, browns and greys.

Known in China as "longxianxiang," which translates to "the fragrance of a dragon's saliva," its origins were unknown until the 19th century, but it was greatly prized for centuries before that due to its wondorous aroma.

Found in small deposits floating on ocean waters - primarily the Indian Ocean - or washed up on beaches, initial theories were that it was formed from bee nests that had fallen into the sea and been transformed.

According to legend, ambergris was presented as a tribute to the Emperor of Persia in the sixth century and Princess Shahrazad, of The Arabian Nights, makes frequent mention of the material in her tales to King Shahryar. For many hundreds of years afterwards, it was in great demand as a raw material for perfumes that were prized by the emperors of Byzantium and the royals and nobles of medieval Europe.

Eventually, however, whalers discovered ambergris inside the bodies of sperm whales. Research later indicated that the substance often contained the beaks of giant squids and it was learned that the whales secrete a substance from their intestinal walls to envelope and ease the passage of squid beaks and other sharp objects that they digest.

But with the ban on commercial whaling in place, it has become nearly impossible to obtain ambergris and examine more closely how it is produced. And while synthetic versions have been developed for the fragrance industry, genuine ambergris has become the stuff of legend.

Conducting some research several years ago, researchers from Japan's Kanebo Cosmetics Inc. learned that a sample had been carefully stored at the National Museum of Nature and Science in Tokyo.

Working with the museum, a tiny quantity was excised, dissolved in alcohol and left to mature at a low temperature over a period of several months. When filtered, the end product was the essential oil of ambergris - a dark brown liquid with a distinctly sweet, woody, marine scent.

The scent will be released at the upcoming "Great Mammals Exhibition:" Inhabitants of the Seas," which opens at the museum in Tokyo's Ueno district on July 10.

Exhibition dates: July 10 - September 26

Access: The National Museum of Nature and Science, 7-20 Ueno Park, Taito-ku, Tokyo 110-8718, Japan. Tel. +81 3 5777 8600.

Entrance fees: Adults Y600 (€5.34), high-school students and younger free. Access is free to anyone aged 65 or older. An extra fee may be charged to enter special exhibitions.

Opening hours: 9 a.m. to 5 p.m. and until 8 p.m. on Fridays. Closed on Mondays.

Museum website: