Old marking system of gold (and other metals)

Do you know some old system of marking gold (and other metals) that was in use in Russia? For example a golden thing that was marked between some certain years (eg 1880-90?) was marked A18 or something like this (I don't have any things at home to see the mark better)?

I have heard of some book where there is some examples of this kind of system. What do you say?

The comprehensive book on the subject is "Goldwork and Siverwork of the XVI - XX Centuries" by Postnikova-Lyoseva.

Essentially the Russian system is this:

Based on Zolotniky, or parts of gold or silver. 

Gold: 56 Zolotniks is 14 karat. 58 is 18k

Silver: 84 is the most common seen. It is slightly less than British or US Sterling.  90 is the equivalent of Sterling, most items exported to England are 90 so they could be hallmarked Sterling.

I have seen 82, 85, 86, 88, 90, and 92 on silver.  Mostly earlier in the 19th century, by the Nicholas II era, 84, 88 and 90 are seen.

There will also be a town mark, and an assayer's mark on all gold and silver items. 

How come some Russian emigrants say that 14K didn't even exist in Russia those days.

This is a too difficult topic for me who don't have any knowledge in this matter, I only have some tiny things and I am not even able to post photos of them.