Sharon Tate's Sister She Was NOT Wearing Ring When She Was Murdered

11/22/2011 6:08 PM PST

Sharon Tate's Sister Debra -- She Was NOT Wearing Ring When She Died

The Sharon Tate "engagement ring" hitting the auction block next week was NOT taken off the actresses' dead hand after she was murdered ... because she was NOT wearing any rings at the time of her death ...  this according to Sharon's sister Debra.

Debra tells TMZ ... the ring featured in an upcoming auction on DID belong to the actress ... but she gave it away to a family friend long before she was killed by the Manson family in 1969.

Debra tells us ... the ring was not an "official" engagement ring -- but rather an "unofficial symbol of her relationship" with Roman Polanski. Debra says, "The ring was not Sharon's style and she never wore it."

Debra says Polanski later gave Sharon an "official" engagement ring -- a gold and diamond band "which she treasured."

Despite the auction house's claim, Debra is adamant Sharon was NOT wearing ANY rings on her finger at the time of her death -- adding, "Because Sharon was pregnant, she couldn't fit any rings on her finger."

Sharon was two weeks away from her due date when she was murdered.

So far, no comment from the auction site.