void ApplyAdditionalHP(object oPC, int iAmount, float fDuration)
{
    effect eHP;
    eHP=GetFirstEffect(oPC);
    while(GetIsEffectValid(eHP))
    {
        if(GetEffectType(eHP)==EFFECT_TYPE_TEMPORARY_HITPOINTS)
        {
            RemoveEffect(oPC, eHP);
            SendMessageToPC(oPC, "Removing Existing HP Buff");
        }
        eHP=GetNextEffect(oPC);
    }

    eHP=EffectTemporaryHitpoints(iAmount);
    ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eHP, oPC, fDuration);
    eHP=EffectVisualEffect(VFX_IMP_HOLY_AID);
    ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eHP, oPC, fDuration);
}

void main()
{
    object oPC = GetItemActivator();
    object oItemToTake1 = GetItemPossessedBy(oPC, "Diamond");
    if(GetIsObjectValid(GetItemPossessedBy(oPC, "Diamond")))
         {
            if (GetItemStackSize(oItemToTake1) > 1)
                {
                SetItemStackSize(oItemToTake1, GetItemStackSize(oItemToTake1)-1);
                }
            else
                {
                DestroyObject(oItemToTake1);
                }
            ApplyAdditionalHP(oPC, 1000, 3600.0);
          }
}