He wanted to impress his future father in law and apparently using a diamond ring worked. The finger on which the promise ring is worn depends on the type of the ring. If men's promise rings are exchanged as a symbol of friendship, then it is common to wear them on any finger including the thumb on the right hand.
Explanation of Cut, Color and Clarity of This Diamond
Cut Quality Diamonds of premium cut proportions are almost as good as ideal. Most people will not be able to distinguish an idea cut from premium. Less diamond material is lost in the process of cutting thus making the diamonds less expansive then ideally cut ones. In short premium cut reflects almost as much light as the ideal-cut, but for a lower price.
Color An E color diamond is extremely rare and slightly less expensive than a D but is so similar that most people won’t be able to tell the difference. You pay a serious premium for an E color diamond. Diamonds of this color grade will appear colorless even when observed face down.
Clarity Typically VS2 diamonds have minuscule inclusions. Inclusions in VS2 clarity grade should be mainly light-colored and completely invisible to the naked eye. Very small dark inclusions are allowable under the girdle when view under 10x magnification. Diamonds in VS2 category are great choice for people looking to balance high clarity and affordable price.