Idiom translation help?

[Don Edwards 548]

Mainly for Old Hack.

On another forum a Danish expression was mentioned. "Do not sell diamonds for goldfish." Can you clarify what that's supposed to mean? Is there anything to it other than the relative values of the two items?

[ProfessorTomoe 1,308]

The intrinsic values of the two would appear to be at the root of the idiom, IMHO. Diamonds worth much, goldfish shiny and apparently worth much, but deep down, not worth anything. Look deep into your deal before you commit, I'm guessing.

@The Old Hack Am I anywhere in the neighborhood?

[The Old Hack 2,448]

...I have honestly never heard this expression before. It could be from one of the dialects. I'd offhand say you are both right, a goldfish looks shiny but kinda doesn't last as long as a diamond.