What is the color and structure of CrO3?
According to its Wikipedia page:

Color

$\ce{CrO3}$ is a dark-purple solid under anhydrous conditions, that turns bright orange when wet.

Production

$\ce{CrO3}$ is generated, as you said, by the following reaction:

$$\ce{H2SO4 + Na2Cr2O7 -&gt; 2 CrO3 + Na2SO4 + H2O}$$

Structure

Its monomeric structure is predicted to be pyramidal like so:



Its crystalline structure is: 



Each chromium center shares two oxygen centers with neighbors, but two oxygen atoms are not shared, giving the overall stoichiometric ratio of 1:3.