Education needed

[BritishTony]

As an ignorant Britisher is anyone able to explain to me what “diamond in the back” means? It’s a complete mystery to me.

[milven]

Interesting question. I always thought that it referred to the Cadillac Coupe De Ville convertibles of the seventies that had a diamond in the back of the convertible top. But if it did refer to that, why would the convertable need a sun roof top? Answer from an ignorant American;)

https://cdn-fastly.thetruthaboutcars.com/media/2022/07/19/9304445/junkyard-find-1975-cadillac-coupe-de-ville-custom.jpg?size=720x845&nocrop=1

[motony]

diamond in the back was referring to the shape of the pad which would have had the TV antenna on the back of the car.

[Sotosound]

"Diamond in the back" is saying that the rear passenger compartment of your limousine is massive.

In other words, you're cruising around in a limo with so much room in the back that it's the size of a baseball diamond.

Bragging? Of course!