David,
if you really want to do it right, you´ll have to do it yourself. I
doubt that the designer understands the intricacies of profile
conversion.
The right way to do it is a DeviceLink conversion (with the proper
DeviceLink).
AdobeRGB as well as sRGB are matrix based profiles and as thus don´t
bear rendering intents other than relative colorimetric. Since
AdobeRGB is considerably larger than sRGB (especially in the
greens), a profile conversion will result in clipping – you´ll lose
detail, especially in the green area. E.g. the following AdobeRGB
values will all result in the same sRGB values:
AdobeRGB -> sRGB -> Lab
0, 255, 0 -> 0, 255, 0 -> 88, -79, 81
64, 255, 0 -> 0, 255, 0 -> 88, -79, 81
128, 255 0 -> 0, 255, 0 -> 88, -79, 81
or:
0, 255, 64 -> 0, 255, 20 -> 88, -79, 79
64, 255, 64 -> 0, 255, 20 -> 88, -79, 79
128, 255, 0 -> 0, 255, 20 -> 88, -79, 79
While a DeviceLink conversion would give you:
AdobeRGB -> sRGB -> Lab
0, 255, 0 -> 0, 255, 0 -> 88, -79, 81 (depending on the settings
in the DL)
64, 255, 0 -> 0, 230, 19 -> 80, -73, 73
128, 255 0 -> 4, 248, 0 -> 86, -77, 79
0, 255, 64 -> 0, 224, 78 -> 78, -69, 56
64, 255, 64 -> 0, 229, 72 -> 80, -71, 60
128, 255, 0 -> 0, 249, 48 -> 86, -77, 73