As safe as you can be with a million dollar necklace around your neck... But you're safe from legal civil forfeiture. Abusive forfeiture is a whole other matter entirely and (IANAL) I'm willing to bet the ones committing the abuse will get the presumption of innocence and you will have to prove the abuse.
not necessarily; If the police recently busted a <gun ring/drug deal/insert generic illegal activity> paying for goods with that same style necklace(or any mental gymnastics to link the item type to a crime) then they could seize it as surely it is part of illegal activity.