Star Diamond Corporation Announces Engagement With Misty Clifton and SGS for a Pre-Feasibility Study on the Star-Orion South Diamond Project

September 9, 2025, Saskatoon, Saskatchewan, Canada – Star Diamond Corporation (the “Company”) (TSX: DIAM) is pleased to announce the engagement of Misty Clifton Engineering LP (MCLP) and SGS Canada Inc (SGS) for a Pre-Feasibility Study (PFS) on the Star – Orion South Diamond Project (the “Project”).

The PFS will build on the revised Mineral Resource estimate, which was completed in 2024 and the technical work completed for and since the 2018 Preliminary Economic assessment (PEA). Significant parts of the work completed for the 2018 PEA, including the mining method, process plant design, site layout and infrastructure, can be updated and incorporated into the updated PFS. The consultants have estimated the PFS will be completed during Q4 2026.

MCLP is a majority-Indigenous-owned entity (67%) formed with Kineepik Métis Local and Mistawasis Nêhiyawak, co-owned and operated by Clifton Engineering Group Inc. MCLP has a long history of delivering engineering solutions for the Star and Orion South project sites, completing numerous foundation, groundwater and slope stability assessments in support of the project for more than 15 years. MCLP has a local team of principal level technical experts in hydrogeology, hydrology, rock mechanics and regulatory approvals. MCLP will provide PFS level geotechnical, hydrogeological, tailing management and environmental engineering services in support of the Project.

SGS has been involved with the project for over 20 years and were the lead consultants in the completion of the 2018 PEA. They have an experienced engineering division that can complete all the mine design and civil engineering work. SGS Bateman, a wholly owned subsidiary of SGS, will be updating the process design. They have been a diamond processing plant design and construction company for over 100 years.

SGS will be supported by Takraf GmbH in the application of continuous mining systems for overburden removal. Takraf is one of the world’s leading manufacturers of surface mining and heavy haul equipment most recently working with Star Diamond on mine design and equipment selection for the 2018 PEA.

MCLP and SGS will be supported by ACA Howe International, who are responsible for the Mineral Resource, Project QA/QC, exploration history and geological modeling for the Project. Working alongside ACA Howe for the Mineral Resource estimate, is Ravenscroft Mining Advisors. Ravenscroft Mining Advisors will be working with Star Diamonds in-house Diamond Specialist Nelson Karun on diamond price modeling and mitigation of risk in diamond price estimates.

Ewan Mason, Chief Executive Officer and Chair of the Board of the Company, said: “Our technical team has assembled an excellent group of consultants who have extensive prior experience on the Project and we are confident they will apply their expertise in a rigorous way to maximize the economics of the Project.”

About Star Diamond Corporation

The Company is a Canadian-based corporation engaged in the acquisition, exploration and development of mineral properties. Shares of the Company trade on the Toronto Stock Exchange under the trading symbol “DIAM”. The Company’s most significant asset is its interest in the Fort à la Corne property in central Saskatchewan. These diamondiferous 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.

Technical Information

All technical information in this press release has been prepared under the supervision of Mark Shimell, VP Exploration, Professional Geoscientist in the Province of Saskatchewan, who is the Company’s “Qualified Person” under NI 43-101.

For further information, please contact:

Star Diamond Corporation Phone: (306) 664-2202 Email: stardiamondcorp@stardiamondcorp.com

Website: www.stardiamondcorp.com

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