Tiffany and Co. Necklaces Hallmark

[twokidsonedog]

Hi there,
Are there any Tiffany experts on this forum who can help me date these two Tiffany and Co. Peretti Diamonds-By-The-Yard necklaces. The first picture shows the Tiffany and Co. mark with no underscoring and the second has the underscoring on all the letters. Any insight on when the signatures were changed? Thanks in advance for your assistance.

 

[chaz]

Not a hundred percent sure on this one,I know in the UK we use a system of date lettering along with the other stamps,such as gold,silver,platinum etc, have a look there and if the date letters are different that should give you an indication of the year if you know how the letters if the have them in the US run?

 

[simpleplan]

the first one's font is something i've never seen on any of my chains.

 

[margaritaxmix]

Yeah..I've never seen the lettering on the first one, so I'm guessing it's less recent?