I would change the grey thread to coral when quilting over the coral fabric and grey over the remainder, although the grey looks good too over the coral. That said, I might be tempted to change the colors to match the fabric or use a variegated thread instead, as there are some gorgeous variegated threads out there in regular thread as well as Rayon, which I tend to use a lot in my quilting, as I think it gives the quilt some pizazz.