The meeting of the two title hopefuls saw England legend Taylor keep tidily after nearly two years in retirement before making two off five balls.
Kirstie White’s 73 off 90 balls underpinned the Stars’ 250-6 before the Diamonds recovered from 70-5 thanks largely to 75 off 106 balls from Sterre Kalis.
The Dutch international, Jenny Gunn and late hero Beth Langston all hit fifties to secure a second win in four games with just four balls to spare. Langston hit the winning runs and finished 59 not out off 53 deliveries.
The Diamonds lost four wickets for 12 as they slipped from 58-1 in the 11th over.
Earlier, White’s 15th career half-century in List A cricket advanced the Stars.
She was supported by a series of valuable contributions, including Aylish Cranstone’s 42 not out.
White set the platform before Cranstone gave the innings late impetus with half-a-dozen boundaries off 31 balls.
The Diamonds dropped three chances of varying difficulty in good batting conditions. The pitch was true and the outfield fast.
Taylor was responsible for the first in the second over of the match when Alice Davidson-Richards edged Phoebe Graham behind on one.
Taylor, a replacement signing for England’s Lauren Winfield-Hill and injured Bess Heath, went to her right one-handed and could only parry a chance which would have been classed as a stunner.
Gunn struck twice for the Diamonds, but White harnessed power and invention to put Stars in a commanding position.
That position was significantly strengthened inside 14 overs of the chase as the Diamonds slipped to 65-4, bringing Taylor in as she prepares for The Hundred.
England seamer Freya Davies had home captain Hollie Armitage caught behind and Grace Gibbs trapped Rachel Hopkins lbw and had Alex MacDonald caught at cover.
Taylor only lasted five balls as she was bowled off an under-edge pulling at Dani Gregory’s off-spin to make it 70-5 in the 16th over.
Like Gibbs, it was the leg-spinner’s second wicket.
Gunn and Kalis confidently rebuilt in a 90-run stand, both reaching 50 before Gunn fell to Bryony Smith at 160-6 after 36 overs.
Kalis took the target to 44 off six overs before being run out from deep midwicket, whioch made it 209-7 in the 45th over.
Langston, however, held her nerve to seal a nail-biting success and said: “We’ve had a few close games like that, and it’s always good to come out on the right side of them.
“It’s always good to know we bat down to 11, and we just needed to take it as deep as possible.
“I tried to stick to my strengths. I didn’t feel like I had to change anything. This win should stand us in good stead to make the finals and also give us good momentum ahead of the T20s.”
Diamonds wicketkeeper Taylor remarked: “I felt rusty, but it was nice to dust the cobwebs off, the legs, the back and the hands.
“For a first proper game of cricket, keeping-wise, after a two-year break, I’m pretty happy with that. It was good fun.
“I had the catch! I had it in my webbing and it came out only when I hit the deck.
“It flew, but I did the hard work. It was just that my elbow hit the ground, and I was gutted.”
South East Stars Kirstie White admitted: “It’s a hard one to take – we’re disappointed. When we finished our innings, we were comfortable with 250 because the pitch was tough to score on at stages.
“But I don’t think we nailed the basics, really.
“Credit where it’s due. They built partnerships and chased really well. Sterre and Jenny batted well in the middle for them.
“But we just weren’t up to scratch in the field.”