French decorative gold and stone set buttonhole watch Circa 1900

Rose gold embellished buttonhole watch
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An extremely rare, numbered buttonhole watch embellished with gemstones, probably made in France, circa 1900. The numbered open faced case of this watch, 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 in red, and spade hands. The movement has a cylinder escapement.
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Diameter: 23 mm
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Weight: 11,5 g
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Signed: No name
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The gold version of buttonhole watches, additionally set with gems, is extremely rare.
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BTÉ S.G.D.G. HR 
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 jewellery, H.R is often associated with the maker of the case or movement.