Printing process is high quality original etching (with finely burred incised lines and heavy inks used), aqua forte, l'eau forte. The number 102 is part of the etching plate impression is NOT a number regarding how many etchings made, as it's part of the original metal plate being struck to paper (it's impossible, that the number could be changed on the metal plate, every time the plate impression was struck, but I do not know what the number 102 infers).
Condition is very good (etching was printed slightly askew from original printing process), unused and clean for the age, showing an age patina and some marks on back of card. The paper on etching is more of a heavy parchment paper with a slight sheen and the inside of card has another piece of paper, lighter in color, which is cotton paper. All evidence on the shape, cut, signature, printing process of the card suggests this card was made by artist or a publisher to be made exactly as is (NOT piece together after the fact). Card comes with a very nice clean envelope, which is antique to vintage and may or may not be, the original envelope to card.
Approximate size is 4 1/8 inches by 6.25 inches, with image size being approximately 2.75 inches by 4 7/8 inches. The words underneath are part of the plate impression Eglise St. Gervais (Vue des Quais) " Inside verse reads " With every good wish for a Merry Christmas and happiness in the New Year. The inside inks burred, incised and are an original etching printing process. The item "ANTIQUE RARE PS SIGNED ETCHING ST.GERVAIS CHURCH PARIS CHRISTMAS GREETING CARD" is in sale since Wednesday, April 17, 2019. This item is in the category "Collectibles\Paper\Vintage Greeting Cards\Unused Vintage". The seller is "honeysuckle*day*dreams" and is located in Wakefield, Massachusetts. This item can be shipped worldwide.