The COA might be real, but who ran it? Any lab can print a piece of paper. What you want is a lab accredited to ISO 17025, which means their testing methods meet international standards. In the EU, that's a solid baseline.

Ask: "Is your lab ISO 17025 accredited?" If the answer is vague, dig deeper. You can also look up the lab's name and check their accreditation status online. A reputable supplier will be proud to share that info because it builds trust.