Iran coins question

250 Rials
1387-1388 (2008-2009)
Copper-nickel – 2.8 g – ø 18.5 mm
KM# 1270

250 Rials (Feyziyeh School) – reverse
1387-1390 (2008-2011)
Commemorative: Feyziyeh School
Brass – 2.8 g – ø 19 mm
KM# 1270a

These two coins (500 and 1000 Rials have same problem) are really confusing me.
My coins is 18.5mm, and it is in yellow color....how could a copper-nickel coin in yellow?
But it is definitely not 19mm...

Any one please help me out..

KM1270a says its made of brass.

18.5mm rounds up to 19.  My guess is that the diameter was rounded up when the page was created.

Quote: CeruleanKM1270a says its made of brass.

18.5mm rounds up to 19.  My guess is that the diameter was rounded up when the page was created.

Problem: in the site "Central Bank of the Islamic Republic of Iran"
http://www.cbi.ir/page/1992.aspx
I only found this description:

250 Rials
Description
Denomination: 250 Rial
First Issue: Feb, 2009
Obverse: Denomination in middle, Islamic Republic of Iran above and year of minting below. On either side a wheat sheaf.
Reverse: Feizieh School.
Weight (gr): 2.8
Diameter (mm): 18.8
Alloy: Cu-Ni-Al

Then I think the coin KM # 1270a DOES NOT EXIST.
Someone more experienced can help me.