The vast majority of older Cornish Ware has either a black or a green 'Shield'. Most storage jars with lettered names have the black shield - be VARY WARY of NAMED jars with a Green Shield which have been known to be plain jars that have been "faked". This doesnt apply to all jars but is worth noting. You will find genuine green shields on some of the named pieces such as oil, vinegar and sauce bottles and butter dishes, so dont be afraid of these! Its just the storage jars to be careful of. Both of the normal shield markings occasionally have a letter in the same ink directly above/below the shield - the letter 'O' seems to crop up a reasonable amount of times. We are not sure of exactly what this means.