Are these what are sometimes called "court" or "opera" gloves? Dress gloves in "white" (actually running from pale cream to yellow)...usually made from kidskin doeskin or similar. Usually unlined though.
If so these are usually washable, and are sometimes even marked as such inside. But not always! It depends on the precise leather. If it is fairly stretchy and soft its probably OK but don't hold me responsible! Hand wash or use wool/gentle cycle with a non Ph liquid like Persil Silk and Wool or Lexol leather cleaner. Drip dry without heat. Maybe wear to finish off when nearly dry.