Hello Clarence,
Since I did not receive an answer to my questions, I have decided to proceed with the appraisal of your mother’s pendant necklace watch. Thank you for choosing mearto.com for this appraisal. I shall try to help you with that at this time.
TITLE:
Fine and elegant, ladies, solid gold (18k), diamond and split (1/2) pearl, keyless, pendant wound, open face pendant watch, case No. 122350, movement No. 122350, with a detachable gold link and pearl-set necklace, made in Switzerland for retailer Tiffany & Co., NYC, USA, circa 1900. {Accompanied by a description from Tiffany & Company dating to the year of sale, 1962.}
Case: 24-26mm in diameter (not counting the pendant), a three body, solid gold (likely 18k) with the back cover inset with rose cut diamonds and split (1/2) pearls set into the gold outer cover (The rose-cut diamonds enhance the pearls, giving a particularly beautiful sparkling effect). The gilt bezel is also set with split-pearls while a fluted gold pendant and shaped gold bow set with split pearls sits at the twelve position relative to the dial. There may be a hinged gold cuvette over the movement (not shown). The inside of the cover carries the same case number as the movement. Attached to the trefoil shaped bow is a gold link chain necklace with intermittent placement of whole pearls. Length of chain not known, but quite long.
Dial: Round white enameled dial with Radial Arabic hours, closed minute ring with red Arabic markers placed around the periphery every five minutes. Gilt Louis XVth-style hands and the upper dial marked, “Tiffany & Co. NYC”.
Movement: Not shown but perhaps a size 9’’’(lignes), matte gilt, 8-17 jewels, cylinder escapement, three-arm balance, blued steel flat balance spring, Swiss made index regulator. The movement is most likely signed for the retailer. (The movement information was obtained by studying other similar examples online.)
Condition:
Case – Very good
Dial – Very good with no hairline fractures.
Movement – not evaluated, but assumed genuine, original to this case and functional.
HISTORY, TIFFANY & CO.:
In 1837, in a time when New York City saw dynamic growth, extravagant taste and golden opportunities, twenty-five-year-old Charles Lewis Tiffany and John B. Young opened a “stationery and fancy goods” store with a $1,000 advance from Tiffany’s father. On their way to the new emporium at 259 Broadway, fashionable ladies in silks, satins and beribboned bonnets faced a gauntlet of narrow streets teeming with horses and carriages and the hurly-burly of city life. At Tiffany & Co. they discovered a newly emerging “American style” that departed from the European design aesthetic rooted in religious and ceremonial patterns. The young entrepreneurs were inspired by the natural world, which they interpreted in exquisite patterns of simplicity, harmony and clarity. These became the hallmarks of Tiffany design, first in silver hollowware and flatware, and later in jewelry. This singular style quickly established Tiffany & Co. as the arbiter of taste, elegance and sophistication, which it still is today. The Tiffany & Co. silver studio, where apprentices were encouraged to observe and sketch nature, was the first American school of design. Tiffany first achieved international recognition at the Paris Exposition Universelle in 1867, when, for the first time, an American design house was awarded the grand prize for silver craftsmanship. By 1870 Tiffany & Co. had become America’s premier purveyor of jewels and timepieces as well as luxury table, personal, and household accessories, with customers including prominent figures such as President Lincoln. At the turn of the century the company had more than one thousand employees and branches in London, Paris, and Geneva. Tiffany opened their own factory for making watches in 1872, but this was a short lived effort and they closed in 1876. The operation of that Tiffany factory was taken over by Patek Philippe in 1879. In 1882 President Chester Arthur invited Louis Comfort Tiffany, the son of the founder, to redecorate the White House and by 1900 the younger Tiffany was a recognized world leader in the Art Nouveau and Arts and Crafts movements. In 1902 he became Tiffany’s first director of design. Tiffany designs captured the spirit of the times from the extravagance of the 1920s to the modernism of the 1930s and the aerodynamic age of the 1940s and 1950s. A unique partnership in retailing was celebrated in recent times by Patek Philippe, one of the world's premiere watchmakers, and by Tiffany & Co., one of the world's leading luxury goods retailers. That business relationship began with a handshake agreement in 1851 between company founders Antoine Norbert de Patek and Charles Lewis Tiffany.
COMPARABLES:
~https://www.barnebys.com/realized-prices/lot/tiffany-and-co-belle-epoque-pendant-watch-N4vMk0w4ZT (sold in 2017 for $7500)
~https://catalog.antiquorum.swiss/en/lots/unsigned-lot-303-133?browse_all=1&page=2&q=gold+and+pearl+pendant+watch (no diamonds and no name on watch estimated at $1500-$2500 in 2016 this watch did not sell.)
~https://www.barnebys.com/realized-prices/lot/j-ferrero-and-touchon-and-co-EE1ReA3Nen (sold for $6720 in 2017)
~https://www.barnebys.com/realized-prices/lot/tiffany-and-co-an-18ct-gold-seed-pearl-enamel-and-diamond-set-openfaced-KgLfrJm5n3 (sold for $8906 in 2015)
~ https://www.barnebys.com/realized-prices/lot/tiffany-and-co-an-18ct-gold-seed-pearl-enamel-and-diamond-set-openfaced-jZihMN4Eqr (sold for $10472 in 2017)
https://www.liveauctioneers.com/item/78793900_54065-swiss-platinum-pavandx00e9-diamond-pendant-watc (sold for $2600 in 2019)
https://www.invaluable.com/auction-lot/patek-philippe-a-fine-and-attractive-18k-gold-pea-14-c-d88e5bbc66 (made by Patek Philippe, the very best, sold in 2014 for 15000 Swiss Francs)
PRICING:
Other than the Patek Philippe pendant watch I tried to pick examples made for famous jewelers. The name Tiffany on the watch increases the value by a factor of two, compared to unsigned examples. I also consider anything sold at Christies or Sothebys to be closer to a retail value than a fair market value. My job is to provide you with a FAIR MARKET market value. I believe in today’s demanding marketplace, your mother’s pendant watch and necklace would sell in the $5000-$6000 range with retail prices being close two twice that amount.
I hope that helps you to better understand the watch your family purchased in 1962. Since some of the photos were at a bit of a distance, I spent a good deal of time researching similar examples online before writing this appraisal. However, I am quite comfortable with understanding what is between the covers of this fine little pendant watch. I believe I am in the right ballpark from a pricing point of view.
Thank you for choosing mearto.com for the appraisal.
My best,
David

Dear Clarence,
Thank you for contacting Mearto with your appraisal inquiry. So that I may best assist you, can you please send me a legible copy of the Tiffany letter? I would also like to know the diameter of the case without including the pendant. The above two items are necessary to do the appraisal correctly.
Any chance of opening up the watch case and showing me the inside of the back cover and the movement, or telling me what is written on the inside of the cover? That would be a bonus.
Let me know so that I can proceed with your appraisal ASAP.
Appreciatively,
David