Value: Brightness or darkness of the tooth. To make the tooth brighter, you layer less enamel (translucent) porcelain. To make the tooth darker, you layer more enamel (translucent) porcelain.
Hue: Color of the tooth. Hue is the A, B, C, Ds of the shade tabs. For example with Vita Classical shade guide, A-series are reddish-brownish, B-series are reddish-yellowish, C-series are greyish, D-series are reddish-grey.
Chroma: Dominance of the hue. Chroma is the 1, 2, 3, 4 of the shade tabs. For example, A4 is more dominant reddish-brown than A3.
Dental lab will always use the ideal porcelain shade when fabricating a case. If doctor requests A1 shade, dental lab will select A1 porcelain to fabricate the case. However, the limitation a dental lab has is not Hue nor Chroma, since shade guide provides reference for Hue (A, B, C, D), and Chroma (1, 2, 3, 4). The limitation a lab faces is value, as different patient’s tooth has different value (translucent layer). This means under different lighting, A1 tooth with more enamel (translucent) porcelain will look darker than A1 tooth with less enamel (translucent) porcelain, although they are both A1, because the light passes through the enamel (translucent) porcelain and shows the dentin (body) porcelain more, making the tooth to appear darker. Translucency is only relayed to dental lab by photos or custom shading illustration, so technician knows how to proportionally build the dentin porcelain layer (body), and enamel (translucent) porcelain layer.