The correct name for the ship was "Armando Diaz", not Diez.
She was a light cruiser, displacing 6000 tons, with 8 152 mm guns and a speed of almost 39 kts -- but no armor at all and a lousy underwater protection.
The Regia Marina built six cruisers of this class between the end of the 1920's and the beginning of the 30's.
They looked very similar to the Zara class heavy cruisers you find in GWX, but obviously smaller.
Here you can find some photos and data.
Will anyone ever put these beautiful ships in GWX?
Gute jagd
Buhring