* Note 1: As announced on 31 May 2023, upon completion of a Framework Agreement with the Government of Tanzania and receipt of regulatory approvals for a transaction entered into with Taifa Mining and Civils Ltd, ownership will become: Government of Tanzania (37%), Taifa (31.5%) and Petra (31.5%). Petra will retain control and continue to consolidate Williamson in it’s accounts.

The Williamson mine was discovered in 1940 by Dr John Williamson, a Canadian Geologist, and is the largest economic primary diamond deposit to be in continuous production. Williamson has been successfully mined for over 70 consecutive years, and as such holds the record for the world’s longest running uninterrupted diamond mining operation.

By the 1950s the mine had developed into a successful operation with equipment that was state-of-the-art for its time and a labour force of several thousand. The mine was closely managed by Dr. Williamson until his death in 1958. During this period production was predominantly from near-surface eluvial deposits that had undergone significant secondary diamond concentration, with grades that ranged from 30 cpht to 100 cpht and an annual production approaching 1 Mcts.

In 1958, the mine was sold to an equal partnership between De Beers and the colonial Government of Tanganyika. De Beers operated the mine until 1973. Tonnages and carats produced increased dramatically during this period, but grades dropped to well below 30 cpht as the open pit entered primary RVK (link to glossary) material underneath the near-surface zone of eluvial enrichment.

From 1974 to 1993, the mine was operated by STAMICO (the Tanzanian State Mining Organisation). Grades varied between 5 and 12 cpht and diamond output fell dramatically relative to the previous 15 years to approximately 70,000 carats per annum. In 1993 De Beers returned to Williamson as operators, together with a recapitalisation and ownership restructuring. Production increased to approximately 195,000 carats per annum to 2005. De Beers announced it would be selling its 75% interest to Petra in November 2008, and the acquisition of Williamson in February 2009.

Williamson is renowned for ‘bubblegum’ pink diamonds, including the Williamson Pink, which is considered one of the finest pink diamonds ever discovered. It was found in October 1947 weighing 54 carats in the rough. The mine, then owned by the Canadian geologist and royalist Dr John Williamson, gave the diamond to Princess Elizabeth in 1947 as a wedding present. It was cut into a 23 carat round brilliant and set as the centre of a brooch in the form of a jonquil flower, designed and set by Cartier in 1953 – see our Diamond Heritage.

The mine also produces beautifully rounded white diamonds of high quality.

1. Resource bottom cut-off: 1.15mm.
2. Reserve bottom cut-off: 1.15mm.

Note 1: Williamson was on care and maintenance during FY 2021

2 The segment result includes depreciation of US$5.0 million

Operations at Williamson recommenced in August 2021, having been on care and maintenance from April 2020. FY 2022 was a year of improving the performance of the mine after this 17-month period of shutdown and the operations are now fully ramped up.

Williamson’s production and grade were in line with guidance. Revenue was US$75.9 million, compared with US$4.6 million in FY 2021 when the only diamond sales were the final parcel recovered prior to the mine being placed on care and maintenance. We benefitted from the recovery of an exceptional 32.32 carat pink diamond which was sold for US$13.8 million in the December 2021 tender.

The on-mine cash unit cost of US$13.9/t was in line with guidance. FY 2022 capex was US$3.3 million, which included the costs of preparing the mine for reopening and sustaining the operations.

The Company’s current mine plan for Williamson has a life to 2030, but given that the Mwadui kimberlite hosts a major resource of 37.9 Mcts, there is potential to substantially extend the LOM.

FY 2022 capex was US$3.3 million, which included the costs of preparing the mine for reopening and sustaining the operations.

The focus will be the continued stabilisation of operations following the period of care and maintenance, including increasing throughput and diamond recovery, while ensuring waste-stripping is undertaken at the required rate.

FY 2023 to FY 2025 production, cost and capex guidance remain unchanged for Williamson.

• We are guiding between 5.2 and 5.5 Mt of ROM material to be treated during FY 2023 which reflects the fully ramped up production.
• The total on-mine cash cost for FY 2023 is guided at between US$66 and US$69 million in real terms.
• Capex guidance for FY 2023 is approximately US$9 million and relates to sustaining capital largely associated with waste stripping and fines-residue infrastructure.

Williamson Diamonds Limited (“WDL”) holds a valid and unencumbered special mining licence number 216/ 2005 dated 25 May 2005 in respect of property described by co-ordinates in the special mining licence located in the Mwadui area in the Shinyanga region.

The special mining licence confers on WDL the exclusive right to mine for diamonds in relation to the licence areas until 24 May 2030. The special mining licence may be renewed for a further period, not exceeding the estimated life of the remaining orebody, on the basis more fully set out in the Tanzania Mining Act 14 of 2010 (“the Mining Act”).

In terms of section 87 (1) (b) of the Mining Act, a royalty of 5% is payable on the sale of diamonds recovered by WDL.

In addition, corporate tax at the rate of 30% is payable in terms of section 4 and other relevant sections of the Tanzania Income Tax Act, 2014 together with an export levy of 0.3% of diamond sales.