What does it mean when “18K – 0.750” is engraved on case between the lugs?

WatchUSeek Watch Forums WatchUSeek Watch Forums Kenseiko

"18K – 0.750" is engraved on case between the lugs. What does "0.750" refer to?
Is it plated or solid case?
Thank you.

Recommended Posts

fsOT ………… Bremont – Black STEALTH – U2 Jet MB { Limited Edition to only 75 pieces } DLC 43mm — { A.D. PURCHASED ORIGINAL OWNER !!! }
Bell & Ross … MT Military Type KHAKI GREEN … ceramic … watch BR-03 BR03 92 BR-0392 BR0392-MIL-CE — { A.D. PURCHASED ORIGINAL OWNER !!! }
Event Timekeeper
Bulova Line Book