This mango is from Mexico, and likely had a Florida-type mango as its parent. It was introduced to the US in the 90s by Dr. Richard Campbell.
The fruit have the visual appearance of a Cogshall and the eating quality of a Tommy Atkins, with a fibrous, somewhat insipid flesh.
We discovered several years ago that Diplomatico is extremely susceptible to bacterial black spot, to such a high degree that every single fruit would get consumed by bacterial cankers and split open on the tree, eventually falling off and rotting.
Diplomatico really has no place in anyone’s yard and we have topworked ours into a Cac.