Gilbert Arenas' lady Laura Govan is serving notice to all basketball wives -- there's only one (engagement) ring to rule them all ... and it's the MILLION DOLLAR stone she rocks on her hand.
Laura was out in Calabasas when our camera guy asked her about Russell Westbrook's endearing display of love to his fiancee -- a sick $700k engagement ring.
That's when the bombshell was dropped -- Laura told us she thinks the Westbrook ring is "cute" ... but can't touch the million dollar MONSTER on her ring finger!!
You gotta see this clip -- Govan explains why she DESERVES to rock the massive rock ... and it's clear she's not shy about it.