Diplomas used to be printed on vellum (a synonym for parchment), which is where we derived the slang term “sheep skin” for a diploma. Animal-skin vellum and parchment, which can be made from goat, pig, sheep or calf skin, should not be confused with the modern paper product known as vellum or parchment paper.
This framed, vellum diploma represents the first Agricultural Engineering degree awarded anywhere in the world, to Jacob Waggoner, here at ISU (then Iowa State College) in 1910. The diploma hung on display for many years in the Agricultural and Biosystems Engineering Department. Sadly, vellum is not a good candidate for exhibit in an uncontrolled environment. As a material, vellum is highly sensitive to fluctuations in relative humidity. The diploma had been hinged into a window mat, which is typically a conservationally sound practice for paper artifacts intended for display. However, humidity fluctuations caused the vellum to flex and curl, creating tension at the points at which the document was hinged to the mat, and resulting in the severe cockling evident in the above and below images.
We removed the cockled diploma from its frame and mounting, and then cleaned, humidified, and flattened the diploma here in the Conservation Lab. We then sent the diploma to Digital Initiatives to be scanned. Agricultural Engineering can now have a high-resolution reproduction printed on paper for framing and display, while the original, vellum diploma will be stored safely in the humidity-controlled Special Collections vault — a solution which honors both the significance of the diploma and the physical artifact itself.
Library and Archives Preservation 
I have a cockled vellum college diploma with some mildew and water discoloration. One edge is wrinkled. What would the cost for your conservation lab to do the job?