One question I am sometimes asked concerns the embossed logos on Chateauneuf bottles. There are several of these. As Chateauneuf is the birthplace of the appellation system, it is no great surprise that the community has developed other ways of guaranteeing the wines. If the appellation system guarantees where the wine comes from, the different bottles are used to indicate whether the wine is estate bottled, negociant bottled within the region or bottled anywhere else in the world (please avoid this last category at all costs!)
First, and most simply, if there is no logo at all, it probably (but not definitely!) means the wine has been bottled outside the region, possibly by a negociant (but possibly a bottling company or similar). Many such wines are made from grapes or wines from estates that do not deem them to be of high enough quality to include them in their estate bottlings. These are the wines of supermarket own labels and the like.
The traditional embossed coat of arms - the large crossed keys under the bishop's mitre with the wording round the outside - can only be used by a grower, or proprietaire recoltant, and in case there is any doubt, the label will state mis en bouteille au domaine or chateau. This is the bottle used by estates such as Raymond Usseglio and Domaine de Cristia
The crossed keys represent the keys of the kingdom of heaven entrusted to St Peter. The mitre, or triple crown (tiara), representents the pope's three functions as "supreme pastor", "supreme teacher" and "supreme priest".
Some producers (including Domaine Grand Veneur) have started to use an updated version of this with a larger mitre embossed on the bottle. Again, this is an indication of the wine's pedigree.
The other main bottle used is like the second (the tradional crossed keys) but the keys are much smaller. These are wines bottled within the appellation by negociants. Some may be OK but the question remains, why take the risk when there are some good estate-bottled wines for little more outlay?