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Discussion Starter · #1 ·
Hi all. Not posted in a while but I was wondering what the letters and numbers in Seiko crystal names mean? I get the first three are size, i.e. 320 = 32.0mm, but what about the T or W next, and then the subsequent characters? Any help or pointers appreciated.
 

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The W is for the watertight crystals, The T is for the acrylic crystals that are held in place by a metal tension ring. The tension rings come in two colors silver and gold and that will show up at the end of the part number such as 350W02ANSO would have a silver tension ring 350W02ANGO would be the exact same crystal but with a gold tension ring. The middle number after the T or W are randomly assigned by Seiko to each different crystal and have no meaning at all. Also keep in mind Seiko round up or down the numbers for round crystals, This means a round crystal that starts with 330 often will not measure 33.0 mm exactly. It will often actually be slightly smaller or larger in many cases. It is more like a category than the exact size of the crystal. Then it can get much more complicated if the crystal is faceted or tinted. I am pretty sure there use to be a chart that broke down all of the combinations but this is just the short version.

Michael
 

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Discussion Starter · #3 ·
Thank you Michael for the perfect answer. I was looking at a correct-size crystal for a diver but without the W, so now I know to avoid it. Interesting that the exact sizes can change. I guess you just have to give it a try and see how it works out.
 

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Discussion Starter · #5 ·
Wow, thanks Mike. Keeping that for reference. And it looks like both L or G can denote Hardlex depending on before or after 1990. Much appreciated both of you.
 
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