In terms of hardness, diamond is significantly stronger than a Rupert's drop. Diamond is the hardest known natural material and ranks at the top of the Mohs scale of mineral hardness with a rating of 10 out of 10. It is composed of a three-dimensional network of carbon atoms, giving it exceptional hardness and durability.
On the other hand, a Rupert's drop is a glass object formed by dripping molten glass into cold water, resulting in a peculiar shape. It exhibits interesting properties, such as a bulbous head and a long, thin tail. While a Rupert's drop is relatively strong, it is not as hard as diamond. If the tail of a Rupert's drop is damaged or fractured, the entire structure can experience a rapid release of stored energy, causing the entire drop to disintegrate explosively.
So, while a Rupert's drop can withstand certain forces and exhibits unique characteristics, diamond is considered to be much stronger in terms of hardness and resistance to scratching or breaking.