French decorative 18 carat gold buttonhole watch Circa 1900

Rose gold embellished buttonhole watch
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An extremely rare, numbered buttonhole watch with diamond and ruby embellishment, probably made in France, circa 1900. The numbered open faced case of this watch is crafted from 18 carat rose gold is punched “BTÉ SCDG H.R” on the back and the bezel is alternately set with diamonds and rubies. The white enamel dial has blue Arabic hour numerals, except for the 12 o’clock which is red, and has spade hands. The movement has a cylinder escapement.
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Diameter: 23 mm
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Diameter bezel: 11.5 mm
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Weight: 13,5 g
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Signed: No name
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The gold version of buttonhole watches with additional gemstones is extraordinarily rare. An identical watch No. 23018, also hallmarked “bté sgdg H.R”, was sold at Koller auctions in 2007. This piece was still in the original box, signed Tiffany & Co. and was estimated for CHF 8.000 to 12.000.
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BTÉ S.G.D.G. H.R meaning
On a 1900 buttonhole watch, these letters probably are French patent markings and manufacturer initials:

• BTÉ is an abbreviation for Breveté (Patented).
• G.D.G. stands for Sans Garantie du Gouvernement (Patented Without Government Guarantee). 

This statement was a mandatory legal disclaimer in France under the 1844 law and remained in use until 1968. It indicated that the French government granted the patent without formally assessing the invention’s novelty, value, or technical validity, leaving the patent entirely at the applicant’s own risk. 

H.R
These letters typically represent the manufacturer’s initials or a specific trademark. In the context of early 20^th century French watchmaking and jewelry, “H.R” is often associated with the maker of the case or movement.