Per team policy, terms of the deals were not disclosed.
Vernace, 23, appeared in 12 NHL games with Colorado, recording eight penalty minutes, and 65 games with Lake Erie of the AHL, recording 17 points (three goals, 14 assists), during the 2008-09 season. He made his NHL debut with the Avalanche on Mar. 17 vs. Minnesota.
The 6-2, 200-pound Toronto native has appeared in 174 career AHL games over three seasons with Lake Erie and Albany, recording 58 points (seven goals, 51 assists).
Originally selected by San Jose in the seventh round, 201st overall, in the 2004 NHL Entry Draft, Vernace played three seasons of junior hockey for Brampton of the OHL from 2003-06, recording 124 points (23 goals, 101 assists) in 138 games.
Gratton, 26, appeared in 19 NHL games with Philadelphia last season, recording three points (one goal, two assists) and 57 penalty minutes. He also recorded six points (three goals, three assists) and 56 penalty minutes in 21 AHL games with Milwaukee and Philadelphia.
The 6-2, 215-pound left wing has appeared in 86 NHL games over four seasons with Philadelphia and Phoenix, recording six points (three goals, three assists) and 294 penalty minutes. The Brantford, Ont., native has also appeared in 213 career AHL games over six seasons with Cincinnati, Philadelphia, San Antonio, Hartford and Milwaukee, registering 71 points (35 goals, 36 assists) and 840 penalty minutes. He won a Calder Cup championship with Philadelphia in 2005.
Gratton, who originally signed with Philadelphia as a free agent on July 27, 2004, played three seasons of junior hockey with Sudbury, Kingston and Windsor of the Ontario Hockey League from 2000-03, recording 111 points (50 goals, 61 assists) and 489 penalty minutes in 166 games.