Essex 164 for 3 (Griffith's 60*, Scrivens 48) beat Durham 155 for 8 (Bates 45, Penna 2-26, Smale 2-26, Maqsood 2-26) by nine runs
Cordelia Griffith's bustling knock of 60 from 35 balls laid the foundations for Essex to end their Vitality Blast campaign on a high by seeing off Durham at Chelmsford.
The right-hander shared a second-wicket partnership of 66 from 44 with skipper Grace Scrivens (48 from 39) as the home side posted 164 for 3.
Durham looked well-placed to chase that down after an opening stand of 78 from 57 between Suzie Bates, who top-scored with 45 from 39 and Emma Marlow - but the momentum shifted after the pair both departed in quick succession.
Spinners Abtaha Maqsood and Sophia Smale, who both returned 2 for 26, squeezed the visitors further and their five-match unbeaten sequence came to an end as they fell nine runs short.
With Lauren Winfield-Hill returning to Yorkshire at the end of her loan spell, Maddie Penna moved up to open with Scrivens and their partnership of 63 from 52 provided Essex with a strong start after winning the toss.
Having pummelled Katherine Fraser to the fence twice in her knock of 25 from 29, the hard-hitting Australian was then given out leg before, but Griffith took up the baton with relish as she lifted Sophia Turner over long-on for six.
Griffith's positive running between the wickets, allied with aggressive strokeplay, propelled her beyond her partner as she raced to a 26-ball half-century but Scrivens narrowly missed out on that landmark, caught reverse paddling Sophia Turner.
Durham finished strongly, with legspinner Katie Levick (1 for 24) removing Griffith and she and Sophia Turner gave away just 13 from the last two overs - six of those from the final ball of the innings, dispatched out of the ground by Jo Gardner.
Like the home side, Durham progressed through their batting powerplay without shedding any wickets and Bates' powerful striking kept the scoreboard ticking along as she thumped Kate Coppack for successive boundaries.
Marlow (25 from 23) filled a capable supporting role until her miscued drive off Smale sailed into the hands of extra cover - and Durham lost their other set batter in the next over when Bates holed out off Maqsood.
The legspinner also accounted for Hollie Armitage, bowled attempting a reverse sweep, but former Essex player Mady Villiers (28 from 22) and Bess Heath (24 from 18) kept the visitors in contention, adding a quickfire 40.
However, the task of scoring 17 from the final over proved beyond Durham, who lost two wickets in three balls to stumpings by Amara Carr as Penna closed the game out.
