Here are the top, reputable places to buy pre‑owned watches that include an authenticity guarantee and a seller warranty or strong buyer protection — with a short note on what each offers so you can choose the best fit for your needs.

1. WatchBox — 2-year limited service warranty on pre‑owned watches; strong in-house servicing and global shipping. (watchboxglobal.com)

2. Crown & Caliber — two‑year warranty on pre‑owned watches (company upgraded to 2-year coverage for purchases after Oct 1, 2021); full inspections and in‑house servicing. (help.Hodinkee.com)

3. Bob’s Watches — one‑year service warranty on most pre‑owned watches sold; long‑established specialist in Rolex and other luxury brands (U.S.-only warranty; terms apply). (bobswatches.com)

4. Watchfinder (Watchfinder & Co.) — typically provides a 24‑month warranty on pre‑owned watches and also partners with manufacturers on certain certified pre‑owned programs (e.g., Cartier pre‑owned warranty details). (Watchfinder.com)

5. Chrono24 (Certified & Buyer Protection) — marketplace with large selection; Chrono24’s “Certified” authentication program and escrow/buyer‑protection (money held in escrow; global money‑back window) reduce risk — warranty terms depend on the dealer/listing (look for dealer-backed warranties or Chrono24 Certified listings). (about.Chrono24.com)

6. eBay (Authenticity Guarantee for watches) — many eligible watch listings are authenticated by third‑party experts (authentication service is separate from warranty). Warranty/returns vary by seller/listing, so check the seller’s return policy and any offered service warranty carefully. (eBay.com)

Additional notes and buying tips

• Warranty lengths and scope vary: some dealers provide a service warranty (covers repairs/parts related to their servicing), others pass remaining manufacturer warranty if still valid. Always read the warranty terms for coverage exclusions (water damage, wear, aftermarket parts, non‑authorized repairs, international limitations). (bobswatches.com)
• Prefer dealer/marketplace listings that explicitly state a warranty period and have documented service/inspection records and photos. For marketplace platforms (Chrono24, eBay), prioritize “Certified” or dealer listings that include escrow/buyer protection. (about.Chrono24.com)
• For high‑value pieces (Rolex, Patek, AP), buying from a specialist dealer with an extended in‑house warranty and documented service history is often worth the premium; ask for serial/paperwork photos and return/warranty policy in writing. (bobswatches.com)
• Shipping & returns: inspect the watch immediately on delivery and use the platform’s buyer‑protection window if something is wrong (Chrono24 holds funds in escrow for a set inspection period). (Chrono24.com)

If you want, I can:

• Filter recommendations by budget, brand (e.g., Rolex, Omega), or whether you prefer dealer vs. marketplace; or
• Pull the current warranty wording for any one of the dealers above and highlight key exclusions.