Nickel allergy causes scaly skin just where the nickel touches, not all over the face. Acne causes pimples, not just redness. Ditto for rosacea. Lupus doesn't sound even theoretically possible. Redness without other symptoms can be treated cosmetically with lasers. If this rash is indeed destroying your wife's self-esteem, you may want to look into that. Makeup, especially green-tinted, is another option. Perhaps you should discuss this with your dermatologist, or get another opinion.
Yes, we have thought about lasers. What kind of laser treatment would we look for? She says that makeup makes it worse.
She does have bumps she says. Here is a link to a picture I took of the face rash. http://picasaweb.google.com/tylerChesley/Rash/photo#5221167109656143314
It really alarmed me that laser treatment may even be considered at this stage, without anyone actually being aware of what's at the root of the problem, as if whatever is happening internally to cause the rash continues to happen, lasers surely won't provide any long term solution and could damange her skin into the bargain! I'm not sure if this will be the same for you, but I suffered a similar problem from age 19 to early 20s - the GP went down the same route of considering lupus (because of the 'butterfly pattern' rash) and allergy. Within a few hours my face could flare up from being totally clear, to some prickly bumps appearing across my cheeks to an angry red rash, which was so severe the skin looked burned. Although there was no single cause identified, contributing factors included a severe allergy I'd developed to nail varnish (I wore it happily for years previously, but since then to this day, I can't even be in a room where any sort of varnish is being used without my face turning to orange peel and my eyes puffiing up alarmingly!). Unlike contact dermatitis, allergies don't always show in the area where the substance is actually touching as they're systemic - even just painting your toes could, therefore, cause your face to flare up. She could have developed atopic-eczema (so she could be going through a phase where her system is hyper-sensitive and the rash is being triggered by foods or substances which normally wouldn't affect her, or it could be a sudden photo-sensitivity - as was also the case with me - so she should ensure her face is protected from the sun). Just from my own experience, I'd really recommend that she asks her GP for a referral to an allergy testing clinic for patch-tests to see if this is a cause, as if so, ceasing use of the offending foods/substances could clear the rash up from the inside out, instead of trying to burn it off externally! I remember regularly being in tears at age 19 because my face had flared up so badly, so I really do empathise. Although it was quite some time ago now, I remember that stopping the use of nail varnish - even the 'hypoallergenic' kind - keeping away from nickel-based jewellery and keeping my face protected from strong sunlight did seem to help, and eventually the problem seemed to burn itself out (though I still have to avoid all the above). Good luck and I really hope you find the answer soon.