There was a rumor that Consuelo's wedding gown was by Worth but I don't think it was ever confirmed. Given the status of both Consuelo and Worth, you'd think that it would've been if it was true but I can't say.
Here's another Duchess (the Double Duchess of Devonshire and Manchester) in Worth from the 1897 Devonshire House Ball she threw.
Paris’ House of Worth fashioned a gown for the wife of the 8th Duke, Louise, Duchess of Devonshire, to be worn at Queen Victoria’s Diamond Jubilee Ball, held at Chatsworth in 1897. The gown was made to transform the Duchess into Zenobia, the warrior queen of Palmyra. A concoction of cloth of silver, cloth of gold, brilliants, gemstones, and embroidered with more metalwork, the dress has a peacock feather fan motif at the hem and a train of turquoise velvet embroidered with gold.
This was the description in the Lafayette archive:
"Costume: "...The skirt of gold tissue was embroidered all over in a star-like design in emeralds, sapphires, diamonds, and other jewels outlined with gold, the corners where it opened in front being elaborately wrought in the same jewels and gold to represent peacocks' outspread tails. This opened to show an underdress of cream crepe de chine, delicately embroidered in silver, gold, and pearls and sprinkled all over with diamonds. The train, which was attached to the shoulders by two slender points and was fastened at the waist with a large diamond ornament, was a green velvet... and was superbly embroidered in Oriental designs introducing the lotus flower in rubies, sapphires, amethysts, emeralds, and diamonds, with four borderings on contrasting grounds, separated with gold cord. The train was lined with turquoise satin. The bodice was composed of gold tissue to match the skirt, and diamonds, and the front was of crepe de chine hidden with a stomacher of real diamonds, rubies, and emeralds. Jewelled belt. A golden crown incrusted with emeralds, diamonds and rubies, with a diamond drop at each curved end and two upstanding white ostrich feathers in the middle, and round the front festoons of pearls with a large pear-shaped pearl in the centre falling on the forehead." (The Times, 3 July 1897, p 12c)."
and the dress in b&w