CRI (Color Rendering Index) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light. The measurement is based from 0 to 100 - with 100 being all the colors found in sunlight (a lot).
What makes CRI so important is that many LED lights might offer similar color temperatures and lumens, but when you put them in your room - somehow your room may look "flat". This is often due to a low CRI in the your light which simply doesn't reflect the colors on your new couch or carpet. For example, an smart LED bulb with a CRI of 80 may not reflect that deep red in your pottery, or that subtle caramel variations in your leather couch.
The ilumi A19 and BR30 smartbulbs have a CRI rating up to 97, meaning we can capture nearly all the colors you would see under sunlight. So not only will these lights generate over 16 million colors, they will also reward you with enabling to see the colors in your room you already have.