Quality Assurance
At Sidr & Stone, quality isn't negotiable. Every batch is independently tested for quality and purity markers such as thymoquinone content — because you deserve to know exactly what you're putting in your body.
Independent testing
We partner with Analytice, an ISO 9001-certified French analytical testing service, to independently verify our oil's thymoquinone (TQ) content — the main active compound studied in black seed oil.
Our first batch measured 2.67% thymoquinone (Analytice, August 2025). At a glance:
- 2.67% thymoquinone — measured in our first batch (Analytice, August 2025).
- 100% pure — no fillers, additives, or synthetic compounds.
- Cold-pressed — no heat or solvents used.
Testing methodology
Our oil is analysed using HPLC-UV (High-Performance Liquid Chromatography with Ultraviolet Detection), a widely used method for measuring thymoquinone. It is the same kind of technique used in a 2022 analysis of commercial black seed products (Khaikin et al., Nutrients 2022).
Our certificate of analysis
We publish our certificate of analysis here, so you can read it for yourself. The certificate below is for our first batch (August 2025).
- Test report: R/25/31283
- Test date: 5 August 2025
- Sample: Cold-pressed black seed oil (Nigella sativa)
- Result: 2.67% thymoquinone
- Testing service: Analytice, an ISO 9001-certified French analytical testing service
Why Ethiopian seeds?
Not all black seed oil is equal. We source exclusively from Ethiopia. In one 2024 comparison of Egyptian, Ethiopian and Syrian black cumin oils, thymoquinone made up the largest share of the volatile fraction in the Ethiopian oil (34.8%, against 27.4% and 22.6%) (Molecules 2024). Our seed is grown in the Ethiopian highlands of Gondar and Bale, where black cumin is grown at roughly 1,500–2,500 m.
Cold-pressed & chemical-free
Our oil is extracted using traditional cold-pressing — no heat, no chemical solvents, no shortcuts. Cold pressing avoids the heat and solvents used in some extraction methods, so the oil looks, smells, and tastes as nature intended.
Protected for freshness
Black seed oil is sensitive to light and air. We bottle ours in UV-protected matte black glass with airtight seals to prevent oxidation. Store it in a cool, dry place away from direct sunlight, keep the cap closed, and use it by the best-before date on the bottle. Thymoquinone in a fresh oil can decrease during storage with exposure to heat, light and oxygen (Khaikin et al., Nutrients 2022).
Batch transparency
Every bottle is traceable to its source. For batch-specific information on your order, email info@sidrstone.com with your order number.
Our quality promise
- Every batch independently tested.
- No fillers or additives — 100% pure Nigella sativa oil.
- Ethically sourced from Ethiopian farmers.
- Cold-pressed with no heat or solvents.
- Latest certificate of analysis published on this page.
We believe in radical transparency. Questions about our testing, sourcing, or production? Contact us.