Shade variation:
V1 - Uniform appearance: differences among pieces are minimal.
V2 - Slight variation with visible texture and/or color pattern differences.
V3 - Moderate variation: every piece has the same shades of color, but the amount of a determined color may be different from one piece to another. A color that is not so evident on one piece, may be the predominant one on the other.
V4 - Substantial variation: every piece presents different nuances of color from one another, allowing a unique final result.
