These western butterflies can be a little confusing for us easterners:-)

this pretty girl is S. californica. The orange cap over the blue spot isn't constantly present on S. californica (usually, but not always). Glassberg used that as a key distinction in his book, but the orange is a better indicator. This one has orange next to several submarginal black spots on both hind and front wings, and the large orange spot is very large. Another difference that I think might work (but I'm not sure if it's always true), is that the postmedian black spot above the blue spot on S. californica seems to be bold, fairly large, and strongly angled. On S. sylvanus is seems to usually (always?) be small, and often not or barely angled.