Dr Venetia Porter, head of numismatics at the British Museum, said it was a "significant" and "exciting" collection which was unusual in its size.
Ron Howell, a 59-year-old retired engineer who first spotted the gold, said the find was "a dream come true". At a press conference yesterday at which the haul was unveiled, he described the moment when he realised that the Devon waters which had been investigated for 15 years for cannon were in fact the site of a wreck.
Although the ship has long since broken up and dispersed, shifts in the sea-bed had finally opened up fissures where the treasure had been hidden, probably for more than 350 years.
Mr Howell said: "I saw a little glint in a crack near a cannon which looked odd. I poked at it with a knife and then put my finger in and prised it out.
"I nearly drowned just breathing in excitement, just looking at this object - a gold nugget. We thought it was a boring cannon site and Wow!"
Mr Howell and 13 other members of the South West Maritime Archaeological Group, who come mainly from the Northampton area, continued to dive and found a total of 430 coins dating from 1510 to 1636 and Moroccan jewellery of the same period. Pottery items also found at the site, half a mile off the coast, come from the Low Countries and Somerset.
The site, off Salcombe in Devon, was placed under official protection last month when the Department of Culture imposed an order under the Protection of Wrecks Act.
As Mr Howell recalled his adventure, the Receiver of Wreck, Veronica Robins, announced a proposed amnesty for others who have found treasure in the sea and not handed it in. The penalty for not doing so could include a pounds 2,500 fine.
Dr Porter said the south coast to Morocco was a common trading route at that time. Museum staff were "very excited" by the haul, which they have been analysing, because they had very few coins from this period and the large number would shed light on mint production.
Half were from a ruler known as the "Gold One" because he found so much gold in Timbuktu. The coins had helped to date the jewellery, which is similar to ornaments still worn in North Africa.
Dr Porter said the British Museum hoped to be able to make an offer for the collection, thought to be worth tens of thousands of pounds.
TREASURE UNDER THE SEA
Other recent finds:
The Swan, a 350-year-old man-of-war found in 1979 off the coast of the Isle of Mull; clothing, weapons and carvings.
The 1763 wreck of the packet Hanover was found earlier this year off Cligga Head, near Perranporth in Cornwall. Thought to contain gold coins worth pounds 50m.
Remnants of what could be the world's oldest ship were found in 1992 off the coast of Hampshire.
Henry VIII's flagship, the Mary Rose, was found on the bed of the Solent 30 years ago and eventually raised.Reuse content