Metal ceramic crown on implant looks grayish and unnatural, Can it be done better? (photos)

Cosmeetic dentistry is Art & Science.  You discussed two different problems Opacity and Greyness.    When you have a titanium abutment there is grey color that needs to be masked.  I do not know what type of implant or where it is placed relative to the facial profile of your crown.  This is lab important factor in how difficult it is to mask the grey. Custom zirconia implants can increase space and make masking easies.  The opacity problem is difficult but can be addressed with layerd ceramic materials with a more opage core and more light transmitting covering feldspathic ceramic.  The cement can also be important, a radio-opaque cement can cover the grey.A second issue is the Value of the restoration, this is not color but whiteness.  If you have blue paint you can add white paint and have a brighter lighter blue paint.  It is possible to creat crowns with higher valuesChroma is the color or shade (ie blueness) of the  ceramic material and it is ofter difficult to see when there is excess greying.  You may want to cosider  e-max material layered with either empress or feldspathic porcelain.  I have seen amazing restorations in Porcelain fused to metal restoration.  The opaqueing is fused to the metal.I fequently have my Lab man James Song and his wife Suzie come in to customize color and glazing in my office.  It does appear that additional volume could also be added to that crown to give better color as well.

There are also zirconium abutments which can be used instead of metal ones. This, combined with zirconium crowns or other esthetic options (ie. Emax) can make for an excellent cosmetic result. 

Indeed these cases are difficult, but from the photos you posted, I think there is room for improvement.  Often Zirconia is too opaque, and metal is gray.  There are other material options that provide better esthetics on anterior teeth.