Typically, prime grade has few, if any knots, and these will be of minimal size. There will also be a minimal amount of sapwood defects and filler, if any at all. Where filler is used its colour is carefully selected to complement the wood rather than to match it exactly, and the colour of the filler may vary from batch to batch. There will be a relatively small amount of colour variation in the timber itself.
SELECT / CLASSIC GRADE
Known as either select or classic grade, typically this will have a mix of almost prime boards with other planks which have more knots. Slightly larger knots are allowed in this grade. Heartwood and colour variation in the timber should be expected and there may be some checks (cracks across the growth ring), sapwood and filler. The colour of the filler is carefully selected to complement the wood rather than to match it exactly and it may vary from batch to batch.
Typically, character grade will include both heartwood and sapwood and allows a wider range of colour variation. Knots are larger and you should expect checks (cracks across the growth ring) and possibly some end shake (cracks between the rings). Filler will be used, the colour of which is carefully selected to complement the wood rather than to match it exactly, and it may vary from batch to batch.
Rustique grade timber is a very high feature grade that has the highest amount of interesting knots, gum lines, insect holes, variations in colour and other beautiful imperfections - making it perfectly imperfect.