A frail 77-year-old was left in tears after she answered the door to a thug who wrenched a ring off her finger.
The man, said to be fat and in his 40s, forced his way inside his victim's home, grabbed her left hand and tugged the diamond-encrusted gold and sapphire ring.
Terrified and in tears, the pensioner rang police as her attacker fled her home in Marlow Road, Worthing.
Police said she was too upset to talk about the attack, which they describe as cowardly and callous.
It follows a weekend in which two pensioners died after break-ins, one in Wolverhampton and the other in Leeds.
Officers urged people to be careful when answering the door to unexpected callers.
They have launched an urgent appeal for witnesses to the attack, which took place at about 2.15pm on Tuesday.
A police spokesman said: "This was a disturbing incident leaving the victim upset and in shock."
Anyone with information should call Detective Constable Dave Stubbings on 0845 6070999 or ring the confidential Crimestoppers hotline on 0800 555111.
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