cinnabar is a blood red mineral that carves well and is used in conjunction with gold to produce jewellery.
could this be a gold cover on a cinnabar stone core? any red bits showing on th other side perhaps? i find it hard to believe they'd make that of solid gold. aside from the expense it'd make the keris quite heavy to carry if it were and the balance would be terrible.
or more regionally correct an indonesian talisman container made of gold, silver and cinnabar
you can just make out the dark red-brown stone behind the gold scrollwork.
Linky it's actually from the same site as the hilt.

another indonesian item from the same site. cinnabar more obvious. moluccan
buginese disks, gold alloy filligree over cinnabar, islamic