The register
Ask the register.
Every piece leaves this house with a reference, and before it ships its record is written at this address, permanently. The record can only be written by the hands that made the piece; there is no other door. So the test of a genuine piece is simple and public: the register knows it, or it is not ours.
The register knows this piece.
Its record carries the piece's own seal, drawn from the reference alone; no two pieces share one. If a paper certificate is in front of you, the seals should match by eye.
The register holds no piece with this reference.
Check the spelling first; the dash matters less than the six characters after it. If it was offered to you as ours and the register does not know it, it was not made in this house. Write to atelier@andamanthread.com and we will look with you.
The register could not be reached just now. Give it a moment and ask again.
Why this works
A certificate can be copied; a register cannot. The record behind each reference is written into the house's own ledger while the piece is still on the hook, grows as it is made, and stays for as long as we exist. A missing record is not a lost paper. It is the answer.