Star - Orion South Diamond Project Revised Mineral Resources Estimate Exhibits Significant Increase

TOTAL INDICATED: 72 MILLION CARATS, TOTAL INFERRED: 15 MILLION CARATS

Stock Symbol: DIAM: TSX

SASKATOON, July 24, 2024 - Star Diamond Corp. ("Star Diamond" or the "Company") is pleased to announce a significant increase in the estimated Mineral Resources for the Star - Orion South Diamond Project (the "Project").

Highlights

• Indicated Mineral Resources on Star have increased 22 percent to 34.8 million carats and the grade has increased 20 percent to 19.4 cpht
• Indicated Mineral Resources on Orion South have increased 37 percent to 36.9 million carats and the grade has increased 32 percent to 17.9 cpht
• Star Diamond has determined that no additional bulk sampling is required on the Orion South Kimberlite for the rigorous estimation of these Mineral Resources, and this results in the savings of millions of dollars in exploration expenditures and shaves significant time off the completion of the Pre-Feasibility Study ("PFS").

President & CEO, Ewan Mason said: "Our technical team and outside consultants have been working extremely hard for the last year and a half to arrive at this incredible outcome. Not only has the requirement for a bulk sample costing tens of millions of dollars been removed but we have reduced the time to complete a Feasibility Study significantly. We intend to have a Feasibility Study completed by the end of 2026, with hopes that shovels could be in the ground within 3-5 years, subject to project financing, permitting and updated environmental approvals. Additionally, such a significant increase in grade and total carats across both pipes bodes well for project economics. It is full speed ahead on the PFS".

Revised Mineral Resources Estimate

Table 1. Revised Mineral Resources Estimates for the Star and Orion South Kimberlites

Table Notes Apply to Table 1

1. Canadian Institute of Mining and Metallurgy ("CIM") definitions were followed for classification of mineral resources.
2. Star Kimberlite Units: Cantuar, Pense, Early Joli Fou ("EJF"), & Mid Joli Fou ("MJF").
3. Orion South Kimberlite Units: P3, Pense & Early Joli Fou (EJF).
4. Mineral Resources are constrained within a Whittle optimized pit shell.
5. Mineral Resources, which are not Mineral Reserves do not have demonstrated economic viability. The estimation of Mineral Resources may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing or other relevant issues.
6. There is no guarantee that all or any part of the Mineral Resources will be converted into a Mineral Reserves.
7. Grade values are rounded to the first decimal.
8. The effective date of the Revised Mineral Resources estimate is July 24, 2024.
9. The EJF Inner and Outer kimberlite units for both deposits are based on detailed kimberlite geology recorded from the core logging of the pattern drilling program. The EJF Inner represents coarser grained EJF kimberlite that occurs within the volcanic crater and the EJF Outer includes finer grained EJF kimberlite that lies on and outside the crater rim. This Revised Mineral Resources estimate acknowledges that the transition from Inner to Outer is geologically gradational.

Senior Vice President Corporate Development, George Read said: "Star Diamond is very pleased with the substantial increase in grade and carats in the Indicated Resource category of this Revised Mineral Resources estimate, which has been rigorously prepared to diamond industry standards using meticulously reviewed datasets. Revised diamond grade estimates are assigned to the Company's established geological models for the Star and Orion South diamond deposits using robust parameters consistent with previous studies. Rio Tinto Exploration Canada's ("RTEC") successful development and execution of the Trench Cutter ("TC") sampling program and diamond recovery in the modern Consulmet Bulk Sample Plant, generated a diamond parcel that can be integrated with diamond parcels from previous underground bulk sampling and LDD programs. The TC diamond parcel has improved the overall diamond grade and Size Frequency Distribution ("SFD") used by Star Diamond to estimate the revised Mineral Resources of both Star and Orion South. The consequent reduction in the average diamond price due to the addition of smaller stones from enhanced recovery, is significantly offset by the larger grade increase. We are also pleased to have diamond expert Mr. Peter Ravenscroft supervise this Mineral Resources update after the completion of RTEC's ten hole TC Program at the Star Kimberlite in 2019, as he not only brings over 40 years of diamond resource estimation expertise with some of the major diamond companies in the world, but also clearly aligns our Star - Orion South Diamond Project Mineral Resources estimate with established diamond industry standards. Estimation of these Revised Mineral Resources has taken a more pragmatic approach with careful consideration of the geological controls on diamond distribution. Particular attention has been given to variations in diamond SFD, in addition to diamond grade. This approach has resulted in a substantial increase in the Indicated Resources for both Star and Orion South. The Star - Orion South Diamond Project now has one of the largest undeveloped Indicated Resources found in any diamond project in the world. The diamond populations of the EJF and Cantuar kimberlite units at Star and the EJF kimberlite unit at Orion South have significantly coarse diamond SFD, from which we can anticipate the recovery of large, high quality (Type IIa) diamonds in future production."

The scientific and technical information contained in this press release has been prepared and verified by A.C.A. Howe International Limited ("Howe"), under the supervision of Mr. Daniel C. Leroux, M.Sc., P. Geo. and the Mineral Resource estimation methodology under the supervision of Peter Ravenscroft, FAusIMM, of Ravenscroft Mining Advisors, an independent mining consultant, and a Qualified Person ("QP") within the meaning of National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("NI 43-101") of the Canadian Securities Administrators. This Revised Mineral Resources estimate uses diamond industry standard methods which are rigorously applied to the Star and Orion South evaluation data, acknowledging the significant control that fundamental kimberlite geology has on the distribution of diamonds within these deposits. The goal of the Revised Mineral Resources estimate was to incorporate additional detailed diamond stone size frequency information obtained by RTEC into the dataset previously used in the 2015 Mineral Resource Estimate, with particular interest in the smaller (+1, +3 & +5 DTC), but valuable stones, which were inefficiently recovered in past exploration programs. Advances in processing flow sheets and updated processing technology have enabled the efficient recovery of these small diamonds by modern processing plants. The grade alignment process used by Mr. Ravenscroft in 2015 has been updated with the Star TC diamond data and subsequently applied to the Orion South Kimberlite.

Mineral Resources Estimation Methodology

Revised grade estimates at Star and Orion South have been based on a diamond industry standard approach using alignment of sample diamond size frequency distributions. Peter Ravenscroft explains: "This approach has allowed for the development of unbiased grade estimates that take into account the effects of using necessarily small samples in a diamond deposit with relatively low grade but coarse stone size. At Orion South, it has also provided a means of resolving sampling results from several sampling campaigns with different drilling methodologies and different sample plant flowsheets. Final alignment with underground bulk sample results and block model interpolation with appropriate smoothing has resulted in robust estimates of grade at a required level of detail for feasibility study of the Star and Orion South deposits."

Economic Assumptions

CIM standards and Securities Commission disclosure regulations require that a Mineral Resource can only be declared on a mineral deposit which has "reasonable prospects for eventual economic extraction". The reported Mineral Resource for Star and Orion South are constrained using a Whittle pit optimization. The Mineral Resources reported in Table 1 comprise the kimberlite that is constrained within the optimized Whittle pit shell. Diamond values for this resource statement are based on the June 2024 High modeled prices determined by in-house Diamond Specialist, Nelson Karun. This Revised Mineral Resources estimate includes only stones recovered larger than +1 DTC diamond sieve and considers all kimberlite above 90 metres above mean sea level or to a depth of 360 metres below surface in Star and 375 metres below surface in Orion South, with the surface being defined by the Digital Terrain Model.

Decision on Orion South Bulk Sampling

Star Diamond, working in close consultation with Peter Ravenscroft, has determined that only limited improvements in precision could be achieved by additional, prohibitively costly bulk sample programs, and that the extensive work already completed will allow for robust diamond price estimates on both Star and Orion South, with associated confidence limits allowing for quantified risk analysis as part of the PFS. This conclusion has been reached based on the following:

• Comprehensive sorting and valuation of all stones recovered from LDD and Underground sampling campaigns over the last 20 years, allowing for the combination of sample diamonds into significantly larger parcels.
• Detailed comparison of quality distributions between Orion South and Star, identifying some clear differences as well as some strong similarities, as would be expected from closely located kimberlites in the same cluster.
• Analysis of the relative precision of price estimates from samples of a different size, specifically where prices are influenced by large and high value stones as at Star and Orion South.

Qualified Persons

Peter John Ravenscroft, FAusIMM, is the owner of Ravenscroft Mining Advisors based in Australia. He has a Bachelor of Science degree in Mathematical Statistics from the University of Cape Town in 1979, and the equivalent of a Masters degree in Geostatistics from the Ecole des Mines de Paris in 1985. Peter has practised his profession for 45 years and has been directly involved in resource and reserve estimation, mine planning and project evaluation for a wide range of commodities. This includes more than ten diamond properties in Africa, Australia and Canada while working 7 years for De Beers and 17 years in technical and executive roles for Rio Tinto, where at one point he was Competent Person for all diamond operations in the company. As a result of his experience and qualifications, he is a QP as defined in NI 43-101.

Daniel C. Leroux, M.Sc., P.Geo. is a Senior Associate Geologist of Howe's UK office. He is a member of the Association of Professional Geoscientists of Ontario ("APGO") and the Association of Professional Engineers and Geoscientists of Saskatchewan ("APEGS"). He graduated from Laurentian University with both a Bachelor of Science degree in Geology (1993) and a Master of Science in Mineral Exploration (2013), respectively. Mr. Leroux has practised his profession for over 30 years, of which he has a total of 25 years of direct experience with diamond projects located in Canada, Africa, Russia and South America, including managerial responsibilities for all various exploration stage diamond projects from conceptual grassroots exploration projects to bulk sampling, diamond resource estimation and pre-feasibility to feasibility studies on advanced diamond projects. As a result of his experience and qualifications, he is a QP as defined in NI 43-101.

Next Steps

Star Diamond will file a Technical Report in respect of the Revised Mineral Resources estimate as soon as it is available, and in any event within the regulated 45-day period after this news release. The Revised Mineral Resources estimate will now be incorporated into a re-optimized open pit mine plan for the Project, which will include a re-evaluation of Mineral Reserves and an economic assessment based thereon. It is anticipated this work will be completed during 2024-25 and will result in a revised PFS including a revised statement of Mineral Reserves for the Project, if warranted, and an economic assessment based thereon. Accordingly, the mineral resources and economic assessment previously disclosed by Star Diamond for the Project should no longer be relied upon.

The Project

The Project is located in central Saskatchewan some 60 kilometres east of the city of Prince Albert. The Project is in close proximity to established infrastructure, including paved highways and the electrical power grid, which provide significant advantages for future mine development.

All technical information in this press release has been prepared under the supervision of George Read, Senior Vice President Corporate Development, a registered Professional Geoscientist in the Provinces of Saskatchewan and British Columbia and Mark Shimell, Vice President Exploration, a registered Professional Geoscientist in the Provinces of Saskatchewan and Alberta, who are Star Diamond's QP's under the definition of NI 43-101.

About Star Diamond Corporation
Star Diamond is a Canadian-based corporation engaged in the acquisition, exploration and development of mineral properties. Shares of Star Diamond trade on the Toronto Stock Exchange under the trading symbol "DIAM". Star Diamond's most significant asset is its 100% interest in the Fort à la Corne Project in central Saskatchewan. These kimberlites are located in close proximity to established infrastructure, including paved highways and the electrical power grid, which provide significant advantages for future mine development.

Website www.stardiamondcorp.com

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Caution Regarding Forward-looking Statements

This press release contains "forward-looking statements" and/or "forward-looking information" (collectively, "forward-looking statements") within the meaning of applicable securities legislation. All statements, other than statements of historical fact, are forward-looking statements. Forward-looking information is often, but not always, identified by the use of words such as "anticipate", "believe", "expect", "plan", "intend", "forecast", "target", "project", "guidance", "may", "will", "should", "could", "estimate", "predict" or similar words suggesting future outcomes or language suggesting an outlook. In particular, statements regarding Star Diamond's future operations, future exploration and development activities or other development plans constitute forward-looking statements. By their nature, statements referring to mineral reserves or mineral resources constitute forward-looking statements.

Forward-looking statements in this press release include, but are not limited to statements with respect to the Revised Mineral Resources Estimate; pricing information and other assumptions and parameters; improvement in the Mineral Resource estimate; statements regarding the processing and analysis of, and reporting of results from, the TC bulk samples previously collected by RTEC; the re-optimization of the Star and Orion South open pits; the potential proportion of Type IIa diamonds in the Star and Orion South kimberlites and the potential for recovery of large high quality diamonds; the publication of the Technical Report; and the aim of the Company to undertake a PFS and Feasibility Study and timelines.

These forward-looking statements are based on Star Diamond's current beliefs as well as assumptions made by and information currently available to Star Diamond and involve inherent risks and uncertainties, both general and specific. Risks exist that forward-looking statements will not be achieved due to a number of factors including, but not limited to, developments in world diamond markets, changes in diamond prices, risks relating to fluctuations in the Canadian dollar and other currencies relative to the US dollar, changes in exploration, development or mining plans due to exploration results and changing budget priorities of Star Diamond, the impact of changes in the laws and regulations regulating mining exploration, development, closure, judicial or regulatory judgments and legal proceedings, operational and infrastructure risks and the additional risks described in Star Diamond's most recently filed Annual Information Form, annual and interim MDA.

SOURCE Star Diamond Corporation