My first guess would be, are you using the Denoiser? If so, turn it off and raise the samples. For the best explanaition, watch this video:)
Also, is it intentional, that the part of the glass, that is in front of the table is clear, while the part of the glass statue, that is “above” the table, and has the black background, is blurred? (I guess, it´s depth of field related, and translucent materials don´t work well with depth of field)