As there is no official distinction by the Kazakhstan Mint between the 2,5,10,20 and 50 tyin 1993 “red” and “yellow” types, I became curious how did that distinction appear. And found this video (in Russian) analyzing the issue:
In short, the “red” coins KM 1a, 2a, 3a, 4a, 5a are exactly the same as the “yellow” ones, which is obvious when the author of the video cuts the coins in half - they have the same color, not only weight and size. Only the outside layer of some of the coins has changed the color over time, due to extra components in the metal used. Similar situation was happening with late Soviet rubles, many of which nowadays look yellowish.
Therefore, I would suggest removing the separate pages for KM 1a, 2a, 3a, 4a and 5a, as these are not distinct types of coins, but rather the same coins as KM 1, 2, 3, 4 and 5. Personally, I have even difficulty classifying some of mine, as they are not clearly “yellow” or “red”, but something in between.
When you say “extra components in the metal used” that would match what we currently have, with the “red” type plated in copper and the “yellow” type plated in brass (copper plus zinc). These two metals can often be hard to distinguish over time depending on how they've tarnished.
However, if there is only one type, are they plated in brass or copper? I can't see a composition given in the scan of Schön (unless Me stands for Messing) but, from the look of our images, all could be brass but I don't think all could be copper.
Former Numista referee for banknotes from Ireland, Northern Ireland, Scotland, Wales and Saint Helena.
The metal alloy used in both cases is the same, called L-80: 20% zink and 80% copper, which means that coins are made from brass. It is actually not correct that the coins are plated - if you look at the two coins that are cut in half in the video I referenced above, they are yellow inside, meaning the whole coin is made of brass. Even though the outside part of one coin is reddish, and the other is yellowish. Interesting was that on the yellow coin that was cut in half, the part that was heated up while being cut in half also became red :) Author speculates that it can be the heating process at a certain point that made some of the coins more red than the others? I am not an expert in the technology of coin production, so do not know if that is possible or not.
This finding can be confirmed by Schon catalogue, as Me20 (Messing 20%) is the same 20% zink and 80% copper alloy, not a brass/copper plated coin. Not sure why Krause has separated these types.
Of course, what I should have done was to check if my coins are magnetic. They aren't, proving that we have the wrong composition. In the absence of plating, it does seem clear that there's a single composition of brass. Well spotted indeed.
Former Numista referee for banknotes from Ireland, Northern Ireland, Scotland, Wales and Saint Helena.
Looking at the 50 tyin page, I just saw this comment by someone:
"As far as i know, the KM# 5a does not exist. It is not listed in Schön and not on the Page of the National Bank. There is only the KM# 5 made of Brass (80% Copper, 20% Zinc). KM is wrong. NGC is wrong. The coins, that appear red like copper, are also made of Brass. The Test-Coins are made of Bronze and Copper-nickel and both are larger then the circulating coins. But these coins were minted in Berlin 1992."
There is no referee, so any master referee can amend those pages. It would be nice to have some explanatory paragraph in the comment section of those coins. If you (or anyone else) could request that, I would be glad. I will now move users from “a”s and delete redundand pages.
I am just wondering. Since the coins are clearly “red” and “yellow”, couldn't this be due to a plating? A plating is just some millimetres thick and wouldn't affect the very core of the coin. I'm not even sure you'd be able to see it even when you cut it in half.
Another question would then be, would the plating be thick enough to make it magnetic (or would it even be magnetic)?
I do believe that the difference is very clear, so to group them together seems a little weird. We have split pages for less than this.
The comment “Some coins are yellow while others are red. This difference is due to an alteration of the colour of the outside layer of the coin over time.” Is there any evidence for this? Why doesn't all coins go red by time? After all, they were all minted at the same time.
The toning of a coin will depend upon the environment it is in, so the different appearances don't have to be due to different compositions. You are of course correct that the difference could be due to one being plated and the other a pure metal. However, it seems to have been proven that the coins are not plated zinc as their interiors are clearly a copper alloy. Plating can be detected by a magnet (the centres of the new UK £1 coins for instance) but none of the metals involved here would be magnetic. X-ray analysis of the surface would reveal a plating, especially if different elements were present.
Former Numista referee for banknotes from Ireland, Northern Ireland, Scotland, Wales and Saint Helena.
I completely agree. I also always said that these are not different alloys, but different shades of color of the same alloy. These coins were minted at the newly established Kazakhstan Mint, the technological processes were poorly followed, and some coins turned out to be a slightly different color due to the fact that the metal was exposed to higher temperatures.
These coins were minted at the newly established Kazakhstan Mint, the technological processes were poorly followed, and some coins turned out to be a slightly different color due to the fact that the metal was exposed to higher temperatures.
Then one could say they are a variety of the original coin, and one might want to collect one of each variety? Maybe the date lines should have “Yellow metal” and “Red metal”, so one can keep track if which one they have?
These coins were minted at the newly established Kazakhstan Mint, the technological processes were poorly followed, and some coins turned out to be a slightly different color due to the fact that the metal was exposed to higher temperatures.
Then one could say they are a variety of the original coin, and one might want to collect one of each variety? Maybe the date lines should have “Yellow metal” and “Red metal”, so one can keep track if which one they have?
There is no clear division into "red" and "yellow" metal. There is a smooth transition from red to yellow. It is impossible to collect all shades of color.
There is no clear division into "red" and "yellow" metal. There is a smooth transition from red to yellow. It is impossible to collect all shades of color.
I suspect you're right but can we prove it? If anyone has a number of these coins with a range of colours, could you take a photos of them and post them? Here's my modest collection. Not sure there's that great a range of colours but it perhaps gives us a baseline.
Former Numista referee for banknotes from Ireland, Northern Ireland, Scotland, Wales and Saint Helena.
I believe all 2 tïın's I've seen has been “red” (or call it whatever you want).
In ceh2019's photo I believe that 2 and 10 tïın are “red”, and 20 and 50 tïın are “yellow”. The 5 is probably “red”, since the “yellow” version tends to look more dirty than dark.
I'm saying that anything is wrong or right, I'm just asking if there any sources that can proove that they are all the same. Or is the only evidence a random dude on youtube claiming they are the same? 🤷
Proof is the key. Right now, we have KM saying two types, Schön saying one. We also have me thinking all my coins are yellow (with the 5 tyin the most toned), whilst you think they're a mixture. The opening post said that the Kazakhstan Mint doesn't list two types. Is there a link for that?
Former Numista referee for banknotes from Ireland, Northern Ireland, Scotland, Wales and Saint Helena.
Proof is the key. Right now, we have KM saying two types, Schön saying one. We also have me thinking all my coins are yellow (with the 5 tyin the most toned), whilst you think they're a mixture. The opening post said that the Kazakhstan Mint doesn't list two types. Is there a link for that?
