Japanese imports of polished diamonds in November jumped 9.1 percent on the year to US$67.8 million.
Japan's imports of polished goods surged 46.6 percent in volume terms to 193,305 carats, according to data released by Momozawa & Co.
That led to a drop of 25.6 percent on the year in the average price per carat of imports in November to $350, but a slight rise of 3.6 percent from the October figure.
In the January-November period of this year, the country recorded an 11.6-percent rise in polished diamond imports to US$834.2 million.
Imports in November were, as is usual, down on the figures for October, when stores are traditionally stocking ahead of the holiday season.
Imports dropped heavily compared with October – down 28.4 percent in value terms and a hefty 30.9 percent drop in carat terms.