Imports to Japan of polished goods dropped 24 percent on a year earlier to $53.6 million in February, according Finance Ministry data.
Japan imported more diamonds in carat terms, up 10 percent to 149,219 carats, but the average price dropped 31 percent to $359 per carat.
Japan's polished diamond imports declined by 10 percent to $127.8 million in January-February.
Belgian exports of polished diamonds in February dropped on the year to $1.25 billion from $1.37 billion a year earlier, according to figures published by the Antwerp World Diamond Centre (AWDC).
Meanwhile, exports in volume terms totaled 585,565 carats from 655,196 carats in February 2012. The average price per carat rose to $2,127 from $2,095 in February 2012.
Israel's net diamond exports in the first three months of this year fell 8.3 percent to US$1.60 billion from US$1.75 billion a year before, according to figures published by the diamond administration of the Economy Ministry.
Net polished imports in the first quarter fell 13 percent to US$962 million from US$1.11 billion in the same period last year.
Alrosa's diamond reserves last year increased by around 35.8 million carats, partly as a result of exploration of the Ebelyakh and Gusiny placers, the company's executive committee was told.
Alrosa reported in November last year that it has diamond reserves, proven and probable in Russia, of 630.6 million carats.
Indian polished diamond exports dropped by 35.7 percent on the year in December to US$950 million, according to provisional figures from the Gem and Jewellery Export Promotion Council (GJEPC).
In the April-December period, Indian polished diamond exports plunged 35.7 percent to US$11.5 billion.
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.
Belgian imports and exports of rough and polished diamonds were largely negative in December and for 2012 as a whole, according to data from the Antwerp World Diamond Centre (AWDC).
Exports of polished diamonds dropped 17.6 percent on the year to $997.9 million in December, while exports in volume terms slumped 18.9 percent to 534,667 carats.
Belgium exported polished diamonds with a value of US$1.056 billion in October, down 4.4 percent on the year, according to data supplied by the Antwerp World Diamond Centre (AWDC).
However, exports in volume terms jumped 12.8 percent to 601,054 carats from 532,782 carats, indicating that the price of goods has risen strongly. The average price per carat of polished exports in October was US$569 compared with US$482 in October 2011.
Rio Tinto announced that gross diamond sales dropped to $313 million in the first six months of 2011 from $326 million in the same period a year earlier.
The miner's output declined sharply in the first six months of the year – down by 26 percent to 5.23 million carats.
The company's results showed that increased prices for rough goods helped offset some of the lower volumes.