This is the famous Portland Vase. The one on the left is the original glass constructed in Rome in 25 AD. On the right is the Wedgwood copy.
Josiah Wedgwood borrowed the original glass vessel from the 3rd Duke of Portland. Josiah was convinced that it was the most perfect vessel he had ever seen. He held on to the vase for four years to perfect the manufacturing of his ceramic (Jasperware) copy of the glass vase.
The original glass vase is located in the British Museum and the Wedgwood copy is in the V&A.
I am not sure that the four year effort was worth it. It is sort of a 'dumpy looking' thing. Even though his aim had to be the perfection of the lithophanes. But he also had the terrific sculptor John Flaxman, the younger, so he couldn't go too wrong.