Opera gloves (it seems the name more or less developed at random because this style was so often worn to operas and other such events) are long (elbow-length or longer, usually reaching to the upper arm or even the shoulder) gloves worn by women as an accessory, usually to a formal outfit such as an evening gown or wedding dress. The "elbow-length or longer" part is the key; gloves which cover a substantial portion of the forearm, up to just below the elbow, can legitimately be called "long gloves" or "evening gloves", but never "Opera Gloves".
Most popular during the Regency Era (roughly 1790 to 1814, so you'll see them in a lot of Jane Austen adaptations), the late Victorian Era, Gay Nineties and Edwardian Era (roughly 1870 to 1914), and the World War II years through the early Sixties. Mostly confined to "specialist" fashions since then (wedding gowns, debutante outfits and the like), though there was a minor revival in the 1980's.
Opera Gloves are usually associated with the following character types (not an exclusive list, but these are the types most frequently seen wearing long gloves:
royalty (empresses, queens and princesses) and the aristocracy:
socialites, especially debutantes and stuffy grande dame types:
chorus girls and showgirls in general:
singers, especially opera divas and big-band singers in 1940's movies:
fashion models (in which case said models will probably be wearing Opera Gloves as accessories to their outfits in a Fashion Show):
As noted, Opera Gloves are closely associated with the aristocracy and royalty, especially during the 1870-1914 period, (in fact, gloves in general have been a symbol of royalty and authority for millennia) and many fictional queens, princesses and noblewomen will be portrayed as wearing them as part of their Gorgeous Period Dress. They can also be Fetish Fuel, especially when worn as part of a dominatrix outfit, or if featured in a scene with a stripper (or somebody imitating a stripper) where the ecdysiast slowly removes her gloves, one at a time.
As a general rule, if Opera Gloves are a solid color (usually white) and unadorned except by "points" (three stitched lines on the back of the glove's hand), they are most commonly associated with Gorgeous Period Dress. Gloves with more-or-less fanciful decorations are generally associated with Pimped-Out Dress.
This site contains a huge archive of photographs and other images of every imaginable type of Opera Glove wearer.
A subtrope of Clothing Tropes, Hand Tropes, Gorgeous Period Dress, Impractically Fancy Outfit or Pimped-Out Dress.
Anime and Manga
The Sailor Scouts of Sailor Moon are the best-known examples of this trope in anime.
Another famous Marilyn Opera Glove scene is her "That Old Black Magic" production number from Bus Stop. As Cherie, Marilyn wears a distinctly down-at-the-heels showgirl outfit, including very cheap-looking black opera gloves.
On The Dick Van Dyke Show Rob (Dick Van Dyke) and Laura (Mary Tyler Moore) were going to a formal dinner party in Alan Brady's place, to accept an award for [something]. The group presenting the award was Black. That day they both managed to dye their hands black while making a stormcloud costume for Richie of a school play. They both wore Opera Gloves to cover their hands (Rob stuffed the gloves up his sleeves) in order to cover up their hands lest their black hands be misconstrued; but Rob revealed the truth to the group, and a good laugh was had by all.
Because the delicate leathers and fine fabrics needed to make gloves were so hard to come by for so many years, a Real Life trope grew up over the centuries in which gloves (until the 16th century largely an article of male wear) became closely associated with aristocracy and authority. Logically, therefore, the first women recorded as wearing gloves in the 16th Century were noblewomen (chief among them Queen Elizabeth I and Catherine De Medici). One of the first women pictured wearing what we today would think of as ladies' long gloves was England's Queen Anne, at the beginning of the 18th Century.
As noted above, Opera Gloves of the mousquetaire style were popularized in Europe and America in the early 1870's by the legendary actress Sarah Bernhardt, who reportedly wore long gloves to make her arms (which she considered to be too thin) look more attractive.
The Empress Josephine is said to have worn long gloves for the same reason, and also did much to make the style popular in post-revolutionary France. (For that matter, Napoleon himself is said to have owned over 200 pairs of gloves!)
During the late 1940's and early 1950's, Queen Elizabeth II and her younger sister, Princess Margaret, were almost never seen not wearing Opera Gloves at any public event. To this day, the Queen is still known as a great white-glove wearer, though she doesn't really wear the true Opera Glove that much anymore.
Marilyn Monroe appears to have loved Opera Gloves: she wore them (and other styles of gloves) on many, many occasions during the glory days of her career.
Grace Kelly was famous for wearing white gloves (Opera Gloves as well as other styles of gloves) both onscreen and offscreen.
Audrey Hepburn is another renowned glove-wearer of the past century, though she's best known for wearing the so-called "coat-length" style (about 3/4 of the way up the forearm), rather than Opera Gloves as such.
Dita Von Teese, with her retro style of fashion, often wears Opera Gloves with both daytime and evening wear as well as for her professional engagements.
To this day, debutantes attending the famous Vienna (Austria) Opera Ball, as well as its imitators, are still required to wear all-white outfits, including white Opera Gloves.
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