Exhibit 16.1

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October 23, 2026

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549-7561

Dear Sir/Madam:

We have read the statements made by Cartiga, LLC pursuant to Item 304(a)(1) of Regulation S-K, which we understand will be filed with the Securities and Exchange Commission as part of the Registration Statement on Form S-4 of Alchemy Acquisition Holdings, Inc. dated October 23, 2026. We agree with the statements concerning our Firm contained therein.

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Yours truly,

/s/ BDO USA, P.C.

BDO USA refers to BDO USA, P.C., a Virginia professional corporation, also doing business in certain jurisdictions with an alternative identifying abbreviation, such as Corp. or P.S.C.

BDO USA, P.C. is the U.S. member of BDO International Limited, a UK company limited by guarantee, and forms part of the international BDO network of independent member firms.

BDO is the brand name for the BDO network and for each of the BDO Member Firms.