Antique Marine Sextants

To authenticate an antique sextant, start by examining the arc graduation: on a genuine period instrument, the scale is hand-engraved or pantograph-cut with a fineness and regularity that modern reproductions rarely match. Look for a maker's nameplate or engraved signature — Heath & Co. (London), Husun, Troughton & Simms, or French houses such as Ponthus & Therrode — along with a serial number, typically found on the limb or the index arm. A brass sextant with its original mahogany case retains significantly higher value than an incomplete or reconditioned example.

The condition of the mirrors and coloured shade filters is critical: desilvered or cracked mirrors reduce both the instrument's market value and its readability. Healthy optics can be cleaned gently with isopropyl alcohol and a lint-free cloth; avoid disturbing the adjustment screws unless you have watchmaking experience. The tangent screw and vernier should move smoothly with no excessive play.

In terms of price, a 19th-century marine sextant in good working order typically sells for between £250 and £1,200, depending on the maker, the completeness of the case and the quality of the optics. Signed instruments from major English or German houses, complete with their original box and accessories — spare filters, replacement telescope, adjustment key — can exceed £1,800. To broaden your collection, explore antique scientific instruments or search for antique marine compasses also available on the platform.

On Antiquités en France, every sextant is listed by a verified professional antique dealer who can provide detailed photographs, provenance history and care advice. Contact the dealer of your choice directly for any enquiry or request for a certificate of authenticity.