We all see the existing grades as
G1/G1+/G1++/G1+++ .....
G2
G3
G4
G5
So newbery must have thought why should the "+" be the sole proprietary of G1. Why not do the same for G2 and G3 (thankfully they haven't done it yet for G4 or below but I can see it coming). So they must have started the G2+, G3+
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Looking further down in future, given that ICC has seriously restricted cricket bat innovation by restricting edge and spine, the innovation is going to come from willow grading
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.. dont be surprised if you see grades as Grade 1.1, ...Grade 1.9, Grade 2.1, Grade 2.2 , ... Grade 2.9 etc where a computer takes in number of grains, number of knots, no of blemishes, blemish size, willow color contrast, etc etc and spits out the grade number via some formula
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Retailers will be saying "so and so customer wanted specific bat shape in grade 2.7 but sorry we had one only in grade 2.6!"