I love "estate" jewelry--old jewelry that was previously owned--but there seems to be a misconception that all older jewelry offers better workmanship and finer gems than what is made today. I recently saw something about this on one of the social media sites, and realized I needed to provide some facts to set the record straight and to add some clarity to your understanding of "estate jewelry."
Where jewelry and gems are concerned, just because something is "old" does not mean it offers a better product or better value. While this might be the case, all-too-often it is not. Where old jewelry is concerned, the more attentive one needs to be to making sure the gem(s) in the "jewel" are really what they appear to be!
In my experience, the older the piece, the more attentive one must be. Stones in old pieces are often not what they appear to be, nor what the owner believes them to be. When examined for the first time by gemologists from the Gemological Laboratory of Great Britain in London, the famous "Black Prince's Ruby" that adorns the Queen's Imperial State Crown was found to be something quite different from a ruby. It was discovered that the "ruby" was really a red spinal--a lovely, naturally occurring red gemstone, but one having a much lower value than that of ruby! If it can happen to royalty, it can happen to anyone, and I've seen numerous cases of "mistaken identity" based on a stone's color. In some cases where the stone is natural but not what the owner believed it to be, the value is usually lower, but in some rare cases, the stone is actually rarer and more valuable!
I've also seen many garnet-topped doublets used in old jewelry, imitating stones of every color (this type of imitation is made by fusing a sliver of garnet to the top of an appropriately colored glass bottom, to create what appears to be a much more valuable gemstone). I've also seen "true" doublets in estate jewelry (as well as new jewelry) which are made by fusing together two parts of a genuine stone with a deeper-color bonding agent to create the appearance of a single, larger, much finer-color--and much more valuable--"gem." I've seen many "emerald" doublets made exactly this way: two layers of very pale, very inexpensive emerald held together by a rich, deep green bonding agent to imitate a much larger, much rarer, and much more valuable "gem" emerald! These are called "true doublets."
I've seen jewelry with colored foil between the stone and the metal backing (which is closed so you can't see the stone's underside). This was not uncommon in the 18th century, and in some cases, the period of the jewelry and other workmanship adds so much value that it hardly matters, but you can be sure the original buyers never knew the "pink" topazes in their necklace, for example, were really colorless ... and much less valuable than the pink! Last, but far from least, I've seen many synthetic gems set into old settings that were made long before the synthetic now set within...antique or old settings are often used to dupe the buyer into believing the stone is "real" even though the stone could have been put in the setting yesterday.
Having said all of this to stress the importance of knowing what you really have, there are also many wonderful estate pieces, containing rare gems, and showing intricate workmanship done by master artisans. There is also a distinctiveness in jewelry from by-gone days that makes it stand apart from what is more commonly available today, and the workmanship is often impossible to duplicate today, at any price! Certain "periods" such as the Edwardian period (turn of the 19th-20th century), and Art Deco period (following the Edwardian, from about 1910 - to approx 1930) or the increasingly popular "Retro" period (1940s) are also very collectible and one pays a premium for fine pieces from these periods, and even more if from a particular house, such as Tiffany or Cartier. Each period also reflects certain style characteristics and cutting styles/sizes in the stones used, which have a wonderful allure for many, including me.
For anyone who loves estate jewelry, I recommend reading the sections I've provided on estate jewelry in two of my books (available from gemstonepress.com): in Jewelry & Gems: The Buying Guide (5th and 6th editions) I talk about what to look for, and what to look OUT for when buying estate jewelry, including the different style elements in each period, the major collectible jewelry houses, questions to ask vendors, what to get in writing, and how to check it out; in Gem Identification Made Easy" I devote a chapter to the types of fraud and deception used to imitate "gems" that are often encountered in estate jewelry (such as doublets) and the ways to detect them using simple, portable tools. I also have a book that deals primarily with estate jewelry -- Jewelry & Gems At Auction. While the book was published quite a while ago, the information pertaining to the various collectible periods, the major houses, the style elements of each period, as well as information related to what to look for and to look out for, is as current today as when first published, as is some invaluable information to help you understand the inner workings of the auction houses and how they affect the "pre-sale estimates," reserves, and actual selling prices. You can find out more about each at my publishers website -- www.gemstonepress.com
In any event, I hope you'll find what I've written here useful and that after reading what I've written you'll understand why you can't take anything "for granted" about the stones in old jewelry. To quote one of my favorite historians--
"To tell the truth, there is no fraud or deceit in the world which yields greater gain and profit than that of counterfeiting gems."
This was written in the year 77AD, by the Roman historian, Pliny. Throughout history this has never changed...it has only become more sophisticated and technologically advanced!