Perhaps mixing just a touch of Americolor chocolate brown into regular white buttercream?
Wilton icing color 'ivory' seems to lean too much towards light orange/peach & is not the color I was hoping for and wondered if anyone has a die hard way to get a true ivory. I don't ordinarily have any problem mixing & arriving @ colors that fit the need, but this one has always had me stumped. Brown color seems to give a 'muddy' look to it. ??? Just skip the wilton altogether?