Hobby names is a big mess. It needs to be straightened out, really.
First, the spelling is Isabel, with an A not O as in isobel. It is based on Isabella, on color of her dress(or part of it), which was yellowish-brown. The spelling Isabel is also used for colors in various domesticated animals- zebra finches, parrots, horses etc. Basically, it's already an established name with an established spelling- Isabel. Not Isobel.. maybe it is spelled that way in other countries but here it is IsAbel.
Porcelain is already an established name for a Mille fleur pattern bird WITH lavender. So Porcelain already is "trademarked" for this poultry genotype.
A BUFF with lavender pretty closely matches Isabel color. So a buff lavender could be called Isabel and be okay with it trademarked too. Those do NOT have mottling. Those OEG pictures are awesome examples of an Isabel-it actually is those birds are MOTTLING away from a Porcelain. No body would think to call those Porcelains, right? So why allow Silkies exactly like those be called Porcelain..?
Who ever posted pictures of lavender, mille and porcelain was awesome too.
OK. Anybody who calls an lavender buffl silkie without mottling a "Porcelain" is simply wrong. No mottling? It's Isabel. That simple. IF it HAS mottling too, then it is Porcelain.
This fad did get started with pictures of various lavender buffs without mottling being labeled as Porcelains.. that was wrong and is probably why there is still confusion.
No mottling- Isabel.
Has mottling- Porcelain.