@shannejw thanks Shanne. Bit of a cheat really, but if you’re going to enhance the Blue, It’s go to be Blueberries. I was going to do as you suggested and Photoshop a Blue Banana or Orange but opted for this instead.
@shutterbug49 I used an LED torch (flashlight) to add side lighting and put a Blue filter over the light (the Blue filter being one of my Grandchildren’s plastic bowls) no fancy setup. The Blueberries are sat on top of a Black Woolly jumper (sweater). Now that you ask about filter on the iPhone, I am going to dig out some gel filters I have for my flash in my camera bag and experimental shooting through them, or putting over the flash on the phone. It should work, I have put tracing paper over the phone’s flash to soften the light in the past. So a few things to try, thanks for the inspiration.