Southern Africa-focused DiamondCorp (LON:DCP) was the sector's biggest faller - down by more than 16.6% in late trading.
The group posted a pre-tax loss of £0.247 million for the six months to the end of June compared with a loss of £3.159 million a year ago, after adjustments for a stronger rand exchange rate but reported production delays at the Lace mine.
Administrative expenditure for the period increased to £0.893 million (£0.672 million in 2015). The increase is primarily due to a timing change on audit remuneration, as well as additional administrative expenses as the company is moving from development into production.
Total assets at 30 June were £39.227 million (£32.719 million in 2015) and liabilities were £28.456 million (£25.219 million in 2015).
Cash at 30 June was £0.108 million. After the period end, a further £2.0 million was raised through a share issue.
The company said its diamond sales schedule has been reorganised to maximise attendance by clients who have been absent from Antwerp during various religious holidays as well as the De Beers August sale.
The first tender will now be concluded on 17 September with results announced on 20 September. Subsequent monthly sales will be concluded around the middle of each month.
The group said production from the first mining block on the 310m level at the Lace mine was impacted during August by a number of operational issues, discussed below, all of which have now been overcome.
The diamonds yielded during August remain of a high quality, and four stones larger than 10 carats were recovered, including a 12.7 carat gem diamond. These diamonds will be sold in the October sale.
It said that in light of the ramp-up problems encountered to date, which management considers essentially resolved, the production forecast for the remainder of 2016 has been re-budgeted for 20,000 tonnes in September, 25,000 tonnes in October and 30,000 tonnes in each of November and December.
The company's current diamond inventory is 7,003 carats. It takes between 30 and 45 days for diamonds recovered to move from the mine to Antwerp and be sold. As a consequence, the October sale will be relatively small but monthly sales are expected to build up to the 9,000 carat base case in the budget by December.
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GoldStone Resources' (LON:GRL) auger drilling programme at the Homase-Akrokerri project in the highly prospective Birimian-age Ashanti gold belt of West Africa has begun, with 93 of the planned 120 holes drilled to date.
- Two teams mobilised to conduct 120 hole auger programme
* 93 auger holes completed, remaining 27 holes to be completed shortly
- Multi-purpose reverse circulation/diamond drill rig will shortly be mobilised on site to test the extensions of the current 602,000 ounce delineated JORC resource
- initial programme will comprise up to 2,500m of RC drilling
- rig has the capability to undertake deeper drilling if warranted by the initial results
- Homase-Akrokerri lies 10km from the Obuasi Mine, one of the world's major gold mines, with combined historical and current resource of c.42 million ounces identified to date
The 2015 auger drilling programme identified, among other targets, a 1,500m gold-in-regolith anomaly at the AK02 prospect on the Akrokerri licence, immediately south west and along strike of the 602,000 ounce JORC resource Homase-Akrokerri deposit.
The Akrokerri licence is contiguous with the licences of Anglo Gold Ashanti's Obuasi Mine and the geology within Goldstone's Homase-Akrokerri Project area is interpreted to be similar to that which hosts the Obuasi mineralisation.
The AK02 prospect has been prioritised for the planned RC drilling programme of up to 2,500m, whilst the ongoing auger programme is designed to evaluate areas of ground between the anomalous zones identified in 2015.
The multi-purpose RC/DD rig contracted from Geodrill Limited will be on site shortly and is expected to commence drilling operations towards the end of September.
The DD capability will enable the Company to follow-up on zones of interest identified by the planned RC drilling and to test higher-grade zones of mineralisation beneath the existing resource.
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Metminco (LON:MNC) posts a pre-tax loss of $1.1m for the six months to the end of June - down from $1.9m last time.
Revenue - interest income - fell to $192 from $3,340 but there was a foreign exchange gain of $25,879 against a loss of $270,194 a year ago and administration expenses fell to $116,248 from $131,645.
Managing director William Howe said: "The period has seen the completion of two very significant events for the Company, the first of which resulted in Los Calatos becoming a genuine development option through securing a financial partner and, secondly, our entrance into the gold sector with the acquisition of Miraflores Compania.
"The focus is now firmly on advancing our near term and robust Miraflores Project in Colombia through to Feasibility and construction finance.
"I am pleased we have exited a period of significant headwinds for the sector with two highly promising projects, and we look forward to updating our shareholders as we progress both projects towards development."
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Gemfields (LON:GEM), the leading supplier of responsibly sourced coloured gemstones, will be reporting its final results for the year ending 30 June on 26 September.
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The sector's biggest riser was Zincox Resources (LON:ZOX) - up by 40% in late trading.
(LON:BEM) Beowulf Mining PLC share price was 0p at 4.25p
(LON:BKY) Berkeley Energia Ltd share price was 0p at 45.5p
(LON:CEY) Centamin PLC share price was -2.95p at 142.35p
(LON:CHL) Churchill Mining PLC share price was -0.88p at 24.5p
(LON:CZA) Coal of Africa Ltd share price was +0.16p at 3.33p
(LON:DCP) Diamondcorp PLC share price was -1.13p at 5.63p
(LON:FDI) Firestone Diamonds PLC share price was +1.38p at 45.5p
(LON:FRES) Fresnillo PLC share price was -29p at 1606p
(LON:GEM) Gemfields PLC share price was +1.26p at 41.38p
(LON:GEMD) Gem Diamonds Ltd share price was +6.75p at 128.25p
(LON:GRL) GoldStone Resources Ltd share price was 0p at 2.33p
(LON:HOC) Hochschild Mining PLC share price was -9.35p at 254.45p
(LON:KMR) Kenmare Resources PLC share price was -3p at 265p
(LON:MNC) Metminco share price was 0p at 0.17p
(LON:VED) Vedanta Resources PLC share price was +1.9p at 501p
(LON:ZOX) ZincOx Resources PLC share price was +0.15p at 0.53p