They lost at Edgbaston by 34 runs.
Essex Eagles are through to their first Vitality Blast final after a comfortable 34 runs win over Derbyshire Falcons in the second semi-final at Edgbaston.
Derbyshire had fought back to restrict Essex to 160 for 5 but their batsman had no response to an Essex attack who exploited a slow pitch expertly.
Off-spinner Simon Harmer took a wicket with his first ball and finished with 4 for 19 while slow left-armer Aron Nijjar, who was playing only the second T20 match of his career, picked up three as Derbyshire struggled after Luis Reece had given the chase a decent start with 19 off seven balls.
Essex wicketkeeper Adam Wheater took a brilliant one-handed catch off a thick edge to remove Reece in the second over and the game swung Essex’s way once Harmer came into the attack in the fourth over.
Off-breaks from the Essex captain which turned sharply were too good for Billy Godleman (9), Leus Du Ploy (9) and Anuj Dal, who was bowled for a golden duck when he unwisely advanced down the pitch. Harmer then returned to claim his fourth wicket when Daryn Smit holed out.
Nijjar was no less effective. Having conceded 14 runs from his first four balls he hit back to bowl Wayne Madsen (17) around his legs and Matt Critchley for five. From 81 for 6 in the 11th over there was no way back for Derbyshire. Alex Hughes made 23 before becoming Nijjar’s third victim while Dan Lawrence got the seventh of eight wickets for Essex’s spinners when he bowled Fynn Hudson-Prentice.
Essex had earlier finished on 160 for 5, more than enough as it turned out but still slightly under-par after they had been 93 for 1 in the 11th over.
They only conceded one boundary from the 14th over onwards after Hughes had picked up wickets in successive overs to drag Derbyshire back into contention.
South African Cameron Delport took his aggregate for the season to 408 with 55 off 31 balls including nine fours as he and Tom Westley put on 78 in 8.1 overs for the first wicket.
But Essex lost momentum when Delport drove to mid-off later in the over and Tom Westley (3) top-edged to short third-man in the 11th.
Essex had lost 3 for 18 when skipper Ryan ten Doeschate (1) was lbw to Reece trying to run the ball down to third man and Essex suffered another blow when the seemingly well-set Westley (39 off 34 balls) gave Reece his second wicket in the 14th over as he picked out deep square leg.
Ravi Bopara got to 27 only to mis-time a ramp shot but Adam Wheater found the boundary again in the last over as he made 20 off 17 balls.