** Graphite India GRPH.NS gains ~2% to 574.40 rupees
** Graphite electrode maker buys 6.82% stake in U.S-based GrafTech International EAF.N worth 1.68 bln rupees ($19.1 mln)
** GRPH set for sixth straight gaining session
** Stock flat on YTD basis
($1 = 88.1637 Indian rupees)