The upperside of the male of C. strabo is purplish but may appeared blue in photos. The tornal black mark is poor however.
The costal spot's position can varies, & may be near the band especially in the female.
The 2 species can be very confusing.

Upperside.
http://farm4.staticflickr.com/3171/2...bed018f988.jpg
Mating pair, male on the right.
http://farm9.staticflickr.com/8320/8...3539dde4cf.jpg
Typical male
http://www.butterflycircle.com/check...Sunny-Chir.jpg
Female with costal spot near band; note broad submarginal band/spots.
http://www.butterflycircle.com/check...t-me-not)2.jpg

C. panormus typical male.
http://2.bp.blogspot.com/_0EK80AsaR7...get-me-not.jpg
Typical female. Note shape of submarginal spots in both sexes.
http://www.butterflycircle.com/check...et-me-not).jpg

Both species are found in open areas.

TL Seow