I believe the 8.6g 10 rubles - Nikolai II (1894-1917) has the wrong edge description
https://en.numista.com/catalogue/pieces18722.html
It says
"lettering: ЧИСТАГО ЗОЛОТА 2 ЗОЛОТНИКА 69,36 ДОЛЕЙ ( Э • Б )
Translation: Pure Gold 2 zolotniks 69.36 dolyas (parts) (E B)"
That's the same lettering for the 12.9 g 15 rubles
https://en.numista.com/catalogue/pieces23407.html
which I think is correct for the 15 rubles.
The correct values for the 10 rubles I think is shown on the the
1923 1 Chervonets Trade Coinage
https://en.numista.com/catalogue/pieces26865.html
"Lettering: 1 ЗОЛОТНИК 78.24 ДОЛИ (ММД) ЧИСТОГО ЗОЛОТА
Translation: 1 zolotnik 78.24 parts (MMD) pure gold"
I don't know exactly what the lettering shows on a the 10 rubles but it should have units like this
1 zolotnik 78.24 parts (dolya)
The units are from the old Russian pound
https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement#Weight/mass
There are 96 dolya per zolotnik so
1 zolotnik 78.24 dolya = 96*1 + 78.24 dolya = 174.34 dolya
therefore
4.26580 g/zolotnik * 174.34/96 = 7.7458 g pure gold
7.7456g gold /0.9 = 8.60 g weight.