Your bag is made from calf skins that have been tanned and colored by hand with vegetable dyes.
For the first few months, dark colors and black can be waxed with polish to revive their color. Natural leather bags can be polished and protected with a colorless cream. Don't worry if the leather darkens a little when you apply it! It will dry and recover its beautiful light golden hue.
After 2 or 3 polishing sessions, your black or dark brown bag will no longer need to be waxed with colored cream. It will have taken on its beautiful, intense, brilliant color for years to come. You can use a shoe polish in a round, flat pot like this one: I recommend the French brand Saphir because I think it's the best value for money, and I love the way it smells!