As your website grows in size, the number of landing pages and sub pages beneath them will naturally grow. There are many benefits to having a website that continues to grow over time. Slow, steady growth implies regular content updates and Google has specific reasons when newer web pages will rank better than more established web pages.
There is an inherent problem with a website when it grows, and it's simply the default navigation structure.
The typical website has some kind of navigation on the top and then either the left or right. The navigation is organized with a primary landing page and sub pages. As your website grows very large there will be sub-sub pages too.
Although Google says they will spider the entire internet, they don't do a very good job at digging deeply into every website. Their point of view is that important information will be easy to get to within 1 or 2 links from the home page.
The majority of jewelry sites we work on only have 1 or 2 levels of pages linking from the Home. Larger product catalogs with multiple pages of products do have trouble getting their content recognized by Google. Even the navigation organization of the jewelry education pages will also work against your ranking.
On large websites, you should strive to have all important pages or products within 2 links from the home page. This might seem impossible through the standard navigation, so let's look at an example.
Let's assume you have a product catalog divided into product sections. Starting from your Home page, you would click the link for "Online Jewelry Catalog," then click the link for "Diamond Engagement Rings," and then you're presented with a page of thumbnails of products. That thumbnail page is already 3 pages deep into your site. Clicking any of the thumbnails brings you to the 4th page.
In that scenario it's not likely that Google will index your product pages. So how do you fix this?
Solution: Create a few very specific pages for some items, perhaps everything from a single designer, or maybe all jewelry with blue sapphires. On your home page put a message and a link that says "See our charming collection of Blue Sapphire jewelry" and link to that specific page. This would be a level 1 link.
On that blue sapphire jewelry page, you would then include all the thumbnails and links for the sapphire jewelry. Each thumbnail and link would lead to the product detail page for that single item.
If you're following along, you should realize that we've just collapsed the product details pages from what might be 4th or deeper to 2nd level away from the Home. This has a far greater chance to be indexed by Google.
Just to be clear, we're not suggesting that you replace your normal navigation; this is a complement to the norm and an extra method to help get your products ranked in the engines. If you take this approach, you should create a number of specific pages and change your home page once a month.