The tradition of awarding diploma with graduation certificate covers originated from Harvard University. The first graduation ceremony of Harvard University was held on September 23, 1642. Nine graduates received "art books" in recognition of their achievements. After the ceremony, the school took back every book. It wasn't until 1813 that Harvard University graduates received a diploma with a uniform cover of graduation certificate that they could keep.
The original diploma cover used thin sheepskin, because papermaking was a arduous process centuries ago. The principal of the school and other officials signed the diploma, all written in Latin. Covers of old diplomas before the 1800s all had different shapes and sizes. Before printing the diploma, if graduates need proof of obtaining a Harvard degree (usually used for overseas travel), this is not a simple process.
In 1840, the first woman to receive a diploma was Catherine Elizabeth Brewer Benson of Wesleyan College (formerly Georgia Women's College). However, she is not the only one. There are eleven other women in her graduating class. With the advantage of the alphabetical order of the last name, she ranked first. She may be the first woman to receive a diploma, but not the first woman to receive a degree. The University of Mississippi awarded a first-class degree to women (Alice Robinson and Catherine Hall, December 1831).
It was not until the last century that diplomas were rolled up and tied up with ribbons. You may ask why, because it can roll and unfold the sheepskin countless times without destroying the sheepskin, and certificate tube holder may be required. Since travel scholars used to carry the cover of their graduation certificate with them as proof of their education, the parchment diploma has proven to be quite resilient. Many universities still adopt the tradition of issuing aggregated "symbolic" diplomas at graduation ceremonies.
Usually, the cover of the graduation certificate will be provided for the actual diploma to protect the document. Others can design their diplomas to display. Nowadays, graduates may save or store the cover of their graduation certificate instead of taking it with them. Therefore, strong parchment is no longer needed. Now, diplomas are usually made of high-quality paper or "synthetic parchment" (made of paper dipped in oil), which has an old-fashioned sheepskin look.