u/spreadsheet_gremlin

Right, and the payoff arrives around month six when a pattern becomes visible that nobody could hold in their head.

Left up. Dates, consistent conditions and annotations, which is the standard here.

the timeframe matters as much as the number

Inter-lab variance on this assay runs a point or two either way. Two services disagreeing by that much is agreement, not a discrepancy, and treating it otherwise starts pointless arguments.

The four things a certificate must carry, and what each one is for.

Batch identifier ties the document to your vial; without it the document is about somebody else’s material. Date of analysis tells you when the number was true. Method — column, gradient, wavelength — is what makes the figure reproducible rather than asserted. Individual related substances give you the shape of what else is in there.

Everything beyond those four is welcome. Anything missing from them is a question to ask before you order, and in my experience the answer arrives quickly from the suppliers who have a batch record to draw it from.

Agreed on buying small first. The cost of a test is small next to the cost of committing to a supplier you have not checked.

the source page log is more useful than the score above it

Disagree that reviews are worthless. They are worthless when they say "fast shipping A+++". A dated one naming a compound and a document is evidence.

Careful. "Nobody has tested Core Peptides" is a statement about this board, not about the supplier. Say the first thing, not the second.

Pushing back a little: a missing field is usually presentation, not concealment. Ask for the full document before drawing conclusions.