Marina is wearing a miniskirt by Stella McCartney from the fall winter 2012/13 runway show.
You can shop this skater skirt eiter at farfetch or at My Theresa :
STELLA MCCARTNEY paneled skirt
(farfetch) 
PATCHWORK SKIRT
(My Theresa)
Otherwise, you can find further Stella McCartney fall winter 2012 runway pieces - as well as similar pieces inspired by the runway - in the same tweed fabric, with the same paneled pattern, and/or with the same skater shape.
COAT AND JACKETS
1) Natalie wool-blend tweed jacket
(Net-a-porter) 
WOVEN JACKET WITH CONTRAST KNIT STRIPED COLLAR
(My Theresa) / STELLA MCCARTNEY Tweed jacket
(farfetch) 
2) Iliana crepe-collar tweed jacket
(Net-a-porter) / STELLA MCCARTNEY tweed jacket
(farfetch)
WOVEN JACKET WITH COLLAR
(My Theresa)
3) WOVEN COAT WITH CONTRAST KNIT STRIPED COLLAR
(My Theresa)
PANTS
4) STELLA MCCARTNEY Stretch tweed trouser
(farfetch)
TWEED TROUSERS
(My Theresa)
DRESSES
5) STELLA MCCARTNEY Contrasting panel tweed dress
(farfetch)
6) TWEED AND DUCHESS SATIN MIXED MEDIA DRESS
(My Theresa)
7) Millie tweed and wool-crepe dress
(Net-a-porter)
STELLA MCCARTNEY Contrasting panelled wool dress
(farfetch) / STELLA MCCARTNEY paneled dress
(farfetch)
DUCHESS SATIN AND TWEED MIXED-MEDIA DRESS
(My Theresa)
8) STELLA MCCARTNEY shape dress
(farfetch)
(runway picture credit : GoRunway)
9) Millie woven and stretch wool-blend crepe dress
(Net-a-porter)
STELLA MCCARTNEY 'Milly' Hand-woven Cotton-silk Dress
(farfetch)
(runway picture credit : GoRunway)
10) STELLA MCCARTNEY Skater dress
(farfetch)
