Friends claim Johnny Depp and Amber Heard are engaged.

The 27-year-old actress was seen sporting a black pearl and diamond ring on her engagement finger earlier this week - which she tried to hide from photographers - and although it was claimed it is just a promise ring, sources close to the low-key couple say they are actually to wed.

A friend told Us Weekly magazine: ''The proposal happened a while ago. She just didn't wear the ring.''

Another source says it took Amber a while to make up her mind about the 'Pirates of the Caribbean' hunk's proposal.

The close family friend told ''It happened on Christmas Eve (24.12.13). Amber really took her time to make up her mind

''She turned him down before ... before she said yes. So she waited and was thinking about it for a long time.''

Amber and Johnny, 50, first met when they starred together in 2011's 'The Rum Diary' but didn't get together until after the breakdown of his 14 year relationship with Vanessa Paradis, with whom he has Lily Rose,14, and Jack, 11.

The couple have been notoriously private about their relationship, but made a rare public appearance together on January 11 at the Art of Elysium Gala in Los Angeles.

Amber's ring has been described as a ''large single emerald or princess cut stone in an elaborate platinum setting'' by website MailOnline, who also noted when she was spotted wearing it, the sparkler ''is yet to be sized correctly and thus had slipped around to the side slightly.''