A treasure hunter was stunned when  he unearthed a beautiful and historic gold ring with a rare black diamond set inside it in a muddy field. John Stevens, 42, couldn't believe his eyes when he rubbed off the soil and saw lettering indicating the ring was from the early medieval period, possibly the 11th century.  It is believed the ring would have belonged to a wealthy person either from the Church, or possibly even royalty. Black diamonds are rare today and would have been even rarer nearly 1,000 years ago, having come from Africa. The ring has not yet been valued but is thought it could be worth tens of thousands of pounds. It is currently being examined and will go to an inquest where it will almost certainly be recorded as treasure. Mr Stevens, a businessman from Hinckley, has been metal detecting for 30 years, and this find in his home county of Leicestershire is his most valuable yet. After discovering it he contacted antiquities specialist Brett Hammond from Time Line Originals. Hammond said: "I arranged for him to take it to the finds liaison officer in his area under the portable antiquities scheme. "It was clearly an important item of treasure. It is a gold ring possibly containing a rare black diamond. "It is a beautiful early medieval inscribed finger ring that would have been owned by a very wealthy person, in the Church or possible even royalty. "Common people in that era were not even allowed to own gold, so it must have been owned by a powerful person. "The ring has gone to the coroner pending an inquest and if tests show what we think it is a museum will almost certainly be interesting in acquiring it."  Stevens said he was with friends in a ploughed field when he came across the ring about five inches down. He said: "We have a really good relationship with the local farmer who more or less gives us a free reign on any fields that have no crops growing. "We had noticed a few days earlier that he was busy ploughing up the field in question, so it at once became our target for the day. "I stuck at it for a couple of hours and had only a few interesting artefacts for my efforts. "Then I found an Edward halfpenny and hope returned only to fade again as the day yielded rather less than we had hoped for. "Some of my friends had switched off their detectors and were walking back to their cars. I was about to join them when I got a really good signal. "The others grouped round me as I dropped to my knees and dug to a depth of about five inches, then pulled out a clod of damp soil. From the side of it I could see gold. "One of my friends thought it was a bottle top but as my fingers closed on it I knew it had never wrapped around the top of a bottle. "Then I heard a chorus of "Lucky sod" and "Jammy beggar". We all realised at once that I was clutching a ring that looked at first glance like medieval gold, with what could be a black diamond. "It is boldly inscribed with lettering that certainly looks very early medieval to my untrained eye. "I don't know yet what the letters spell out, but if they indicate a royal owner it might be worth tens of thousand of pounds."