The bullion is held in a form generally accepted in settlements of physical bullion markets around the world. All gold bars held by Vaultoro in the Brinks Switzerland vaulting facility follow the definition of the UK Customs and excise 701/21 notice by being no less than 99.99% pure gold, of weight and by a manufacturer globally accepted by global bullion markets.
Vaultoro guarantees that all gold held in your account is part of a 99.99% minimum assayed bullion bar. All bars (usually from Heraeus or Valcambi) have been manufactured under the high LBMA Good Delivery quality standard.
More information about gold bars: http://www.lbma.org.uk/good-delivery