An engagement ring that Hollywood star Ben Affleck bought for his former fiancée Jennifer Lopez has gone up for sale almost a year after the celebrity couple broke up.

The 6.1-carat pink diamond ring has been "re-acquired" by Harry Winston, according to a spokesman for the New York jeweller, reported imdb.com.

But the ring is available only to "serious buyers", said the spokesman.

Lopez reportedly returned the $1.2 million solitaire to Affleck - who bought the ring in 2002 - after calling off their wedding plans at the beginning of 2004.

Lopez went on to marry salsa star Marc Anthony in June 2004, while Affleck is currently dating his "Daredevil" co-star Jennifer Garner.