NEW YORK - Vivienne Tam embraced geometrical shapes in a very big way Wednesday for both her spring-summer 2013 collection and her brand-new jewelry line on show at New York fashion week.

Her cutting-edge creations - think triangles and hexagons - stood in radical contrast to more feminine looks that have come down the runways over the past seven days.

"It's very geometrical," Tam told AFP before her Lincoln Center show. "It's about the five elements, the very basic forms of the universe... water, metal, earth, fire, er, what else? Wood!"

Tam, a youthful 54, was fire personified backstage in a brilliant orange A-line dress with a chunky octagonal necklace representative of the distinctly modernist flavor of her jewelry debut.

"Jewelry is part of fashion. We can't doubt it," said Tam when asked why she was stretching her creative wings - in this case, in partnership with long-established Hong Kong jewelers Tse Sui Lue - in such a new direction.

Out on the runway, Tam paired a black patent leather shell and monochrome triangle print dress with black gold circle earrings, while a yellow gold hexagonal necklace complemented the glamour of a black silk sheath dress.

Tam didn't neglect polka dots and stripes, sending out the former as a cotton jacket and crop pant ensemble, the latter as a silk dress, and both in black and white.

The New York collections wrap up Thursday with Ralph Lauren and Calvin Klein, after which the spotlight swings onto London, Milan and then Paris. Among other shows Wednesday, champagne awaited guests at Philosophy di Alberta Ferretti as they flocked to the Plaza Hotel for an elegant collection featuring pink bustiers with pencil skirts and shirt dresses over shorts.

"The silhouette is very fine, very clean," Ferretti told AFP, with subtle masculine touches - such as a slick silk suit and tie - sharing the moment with stripes and dotted patterns.

Gilles Mendel, the fifth-generation French designer behind venerable family label J. Mendel, took inspiration from the whimsical Japanese gardens of Kawachi Fuji for his latest flowing looks.

"It's a return to the glamorous moments of the 1940s," Mendel - celebrating his 10th year creating ready-to-wear - told AFP.

For Marchesa, British designers Georgina Chapman and Keren Craig were clearly under the spell of India with their sari-inspired collection that oozed eastern sophistication.