Merry-Lee has explained here the numbering system of the leading manufactures of Japanese enamels..

Color numbers for Japanese enamels.

There are currently three manufacturers of Japanese enamels.. The numbering systems of each can be difficult to understand. We have behind us many years of numbering systems changing. Some due to formulas changing as laws prohibit the use of hazardous chemicals some, materials no longer being available.

Here Merry-Lee has cleared up the three major manufacture numbering systems for today’s enamelist.

Ninomiya is the most widely Japanese enamel known so I will start with it. The N series of transparents were formulated for work on silver. This does not necessarily mean that they are not silver reactive. It just means that they look pretty on silver. They are N plus a one or two digit number.
The L series of transparents are formulated for copper. They include most of the deeper shades as they work well over copper. They are L plus a two digit number. In their opaques, they also have L series, copper formulated and designated by L plus a three digit number. There are also Opaques in the B series which also have three digit numbers. I can theorize that they are formulated for silver but once again there are colors that are silver sensitive.

Their Opals ( which technically are not true opalescent but rather semi transparent or translucent. They are not tricky to use and are very straight forward) all begin with NG and are followed by three digits.

The semi-Opaques all begin with P and are followed by three digits.
In addition there are a few orphans, I am not sure why but include SL5, ND65, ND66, and two others but I am drawing a blank. All transparent. Ninomiya simplified their Lettering system 10-15 years ago. At the time there were some H transparents which were changed to N. Example N13 used to be H13. There were some LT transparents that became L for example LT61 is now L61. Oh yes- there is one N Opaque. N2 opaque white. They currently have no plans to confuse us further by changing their numbering systems.
Unfortunately some distributors change the numbers to make them proprietary. Gah!

Nihon Shippo Japanese enamel has a transparent series G formulated for silver. (Plus three digits) Unlike the other manufacturers of enamels, many of the G pinks and reds are silver compatible. Many of the G series have three different versions of the same color. They standardize those variations with a suffix of A being the lightest, no suffix being Medium and C suffix being the darkest. Let’s call them color families. As an example G701A is super light pink, G701 is light pink and G701C is a slightly darker pink.

Nihon Shippo has copper formulated transparents also. They use no letter. Most are three digits, starting with a 1. Once again they have color families. For example- 109 is a deep orange, 109A is a medium orange and 1090 is a peach or pastel orange. Carrie, who is the product manager at Enamel Art Supply thinks that the 0 (zero) on the end of 1090 is probably an O (oh) and so you will see her writing 1090 with a slash through the second O. Or 109O if you can see the difference. That way all three are 109 but two have a suffix.
Are you guys still reading? Maybe someone should put this in a place where I can find it again!

Thought I’d better post that before I lost it. Nihon Shippo also make Opaques. They are mostly 2 digit numbers. They also make semi-Opaques which are three digits starting with a 2.

On to Hirosawa Japanese enamel. They make a series of transparents formulated for silver that begin with S-. Truthfully Hirosawa calls them HS- but at Enamel Art Supply, we took off that H to try to make them less confusing. They also have color families. For example S-9 is a medium grey. That family includes S-9AAA, S-9AA, S-9A, S-9, S-9B. S-9AAA is the lightest and S-9B is the darkest. Their second series of transparents are H- and two digits formulated for copper. There are two transparent ST that are spectacular silver friendly pink and red.
Hirosawa’s Opaques are H- and three digits.
Their translucent have a prefix of P or PS.

I think all three companies have used systems that work for them and probably developed over time to accommodate a changing product line. By the way, I use the silver and the copper formulas on both silver and copper.

http://www.merryleerae.com/workshops.html

This is very helpful and thank you Merry-lee for bringing all this info together for the world of enameling artist!