Beauty is only ISO deep!

How to read your ISO:

When shooting in low light conditions (like the sculpture studio!), there is not much light available for your camera sensor.  A HIGH ISO number, such as ISO 3200, will increase the sensitivity of the sensor, multiplying the small amount of available light to give you a correctly exposed image.  The "side effect" is what's called "increased noise" on the image, which looks like a fine grain, reducing the overall image quality...most pronounced in the darker/shadow regions.

Present day "Girl with the Pearl Earring"...

You want to keep the ISO as low as possible...the lower the ISO, the less "noise" and the higher the quality of the image.  These are all approximate starting points:

Outside on a sunny day, select ISO 200 and see how it goes.  
If it gets cloudy, select an ISO somewhere in the range of 400-800.  
If you are indoors, consider an ISO of 1600 or above.