Took this using my rashly assembled studio kit using one SB28 firing into a 5in1 reflector setup as a diffuser directly behind the bulb with a piece of black card filling the frame so the light that leaked around the card caught the edge of the glass envelope.
The flash was gelled with a bit of lee 180 from the scraps bag at work large decorative bulbs like this always seem to be slightly out of shape i noticed.
This was done with a different bulb but the same setup more or less, the glass envelop on the bulb was very uneven and caught the light quite differently might retry it but theres only so many times you can reshoot the same object :)