string sDeny;
void main()
{

object oPC = GetLastUsedBy();

if (!GetIsPC(oPC)) return;

if (GetItemPossessedBy(oPC, "BlackDiamond")== OBJECT_INVALID)
   {
   sDeny="*You notice the diamond shaped hole just above the chest's handle*";

   SendMessageToPC(oPC, sDeny);

   return;
   }

object oTarget;
oTarget = GetObjectByTag("rall_chest_plot");

SetLocked(oTarget, FALSE);

object oItem;
oItem = GetItemPossessedBy(oPC, "BlackDiamond");

if (GetIsObjectValid(oItem))
   DestroyObject(oItem);

}