UPDATE 2.20pm: Shares in Lucapa Diamond Company surged after the Miles Kennedy-led explorer announced it had recovered 12 kimberlite diamonds from preliminary surface sampling at its Lulo diamond concession in Angola.
Lucapa noted the stones had been recovered from four distinct Kimberlite pipes and six of the 12 rocks had been confirmed at rare type 2A gems.
Type 2A diamonds are among the world's rarest diamonds, accounting for less than one per cent of global diamond production.
"With a surface area of approximately 220ha, Se251 is the biggest pipe discovered by Lucapa within the two kimberlite provinces discovered within the 300sqkm Lulo concessions," the company said in a statement.
Lucapa said its geologists believed the Se251 pipe was a likely source of the large and valuable type 2A alluvial diamonds of up to 131.4 carats recovered from this area.
Mr Kennedy said confirmation that kimberlite pipes at the Lulo concession hosted type 2A diamonds was another significant milestone for the company.
"The fact we have now identified several diamond bearing kimberlite pipes proximal to where we have found large alluvial diamonds is of great significance as we are really only scratching the surface of these pipes at this time," he said.
"The independent confirmation that 50 per cent of the diamonds recovered are rare type 2A diamonds also adds early credence that these pipes could well be the source of the alluvial diamonds - early but exciting days."
Lucapa shares jumped 12 cents, or 26.37 per cent, to 57.5 cents by the close of trade after emerging from a trading halt.