A definitive decimal currency Five Rupee Stainless Steel coin with a milled edge, first announced on 2016 March 13th and first issued on March 15th(?). It was to circulate along side the older coin which remained legal tender.
Obverse : The Armorial Ensign of Sri Lanka
Reverse : The large numeral 5 at the centre with FIVE RUPEES in Sinhala, Tamil and English superimposed. SRI LANKA in Sinhala appear at the apex and Tamil and English on each side. The year of issue at the bottom. The coin is 2.4 MM thick and does not have any incused lettering in Sinhala, Tamil and English, as on edge of all older Rs 5 coins since 1984.
The 2016 dated coins were put in smaller packs of 100 coins each and 20 were included in the larger pack for simpler distribution. Printed in Black on the small polythene pack was 5 Rupees - 100 Pieces in 2 lines.
Weighing each of the 100 coins on a digital pocket scale with a precision of 0.01 grams, I found that the coins weighed between 7.42 amd 7.58 with a mean of 7.50 grams. The distribution had a rms dispersion of 0.034 (0.45% of mean weight). It had a positive skewness of 0.135 and was platykuratic with an negative excess kurtosis of -0.26. i.e. distribution flatter than normal.
The weight distribution appears non Gaussian shows a number of peaks. The weight depends of the thickness of the planchets that got mixed into the coin pack analysed. Coins from planchets made from the same strip of metal could get preferentially mixed into the same pack and cause the off center peaks that are observed in this weight distribution.
It appears that the coins outside this range have been removed by some weight control. This would reduce measured negative skewness and kurtosis.
The CBSL press release stated All other specifications including dimensions and designs of the above said coins remain same. However the coins are 0.20 grams or 2.6% lighter.
The thickness of the Rs5 coin varies as expected from 2.32 mm for 7.42 grams to 2.37 mm to 7.58 gram coin which are the extremes with 2.35 mm for average 7.50 gram coins.
The coin pack was obtained from CBSL on March 20th. Mint, Mintage and average weight from from CBSL RTI 0006/17. Coin scaned at 600 dpi and the images are displayed at 300 dpi.