Antique 18K Gold Pocket Watch. Possible Patek Philippe. Switzerland circa 1900

Gent's pendant wound and pin set, 18k yellow gold, open face pocket watch. Unsigned, (possible attribution to either Patek Philippe or Vacheron Constantin), made in Switzerland, circa 1890-1910.Case: 50mm diameter, three leaf, 18k yellow gold, open face pocket watch, with a fluted gold ball pendant and round bow placed at the twelve position, with adjacent push button to set the time.The back cover is engine turned and has a shield-shaped cameo with floral engravings for the owner's initials (unengraved). The inside of the cover has a wave like undulating damascened finish and is marked with the case number, 66116, 18k gold and 'L.F.' most likely for the casemaker.The cuvette is marked in French (translated), "Pendant wound, #66116, straight line lever escapement, visible pallet jewels, Breguet Hairspring, 15 Jewels". There are neither Swiss, French nor English gold hallmarks on the case.Dial: White porcelain dial enameled with bold Roman hours, closed bar minute ring, sunken subsidiary seconds ring @6 and Gilt Continental type Spade hands. T&he dial is unsigned.Movement: Half plate and finger bridge, 15 jeweled movement made in the Swiss manner, the crown and ratchet wheels are damascened and have wolf's tooth winding on both gears, moustache counterpoised lever escapement with visible jeweled pallets, bimetallic balance with Breguet hairspring and plain index regulator. The plates and bridges are unsigned except for the fast and slow in French on the regulator.Condition:Very good working condition Case Mint. Dial -Excellent. Movement - We know that other Swiss companies made wolf's tooth gearing in pocket watches, and the best known are Vacheron Constantin, Lepine and LeCoultre, but there were others as well. I am uncertain if other companies, besides Patek Philippe, Vacheron Constantin and Audemars Piguet used the moustache counterpoised lever escapement, but they are not readily apparent to me. The index regulator used here is much simpler than either of those used by P.P. or V.C. So, we can only make a possible attribution here.Date Circa 1890-1910