Make no mistake about it, I am sea glass obsessed and as someone with rampant and unmedicated ADHD (very productive, hyper focused, can't sit still in mind or body, 50 projects on the go at once) I thought why not share my most prominent and genuinely long thought out, itching theories on Seaham sea glass collecting. If you're interested in the history of Seaham and the Durham coastline, I'll make a separate blog post on it shortly, but for now I just want to get stuck in!
"The Multi Line"
This is my own, original, long held private theory on sea glass deposits at Seaham Hall Beach in particular. It is unproven (and as someone who can't swim, I don't want to find out) but to a certain extent it must be true. This thought came to me while trying to get to sleep, circa 1am, watching a documentary on Mariana's Trench and I got to thinking... there must exist trench/s in the North Sea, at lighthouse level, perhaps beyond too, which is heavy in sea glass deposits, stuck tumbling in trenches, eventually being swept out when the sea is tempestuous enough, in only a small cluster. Perhaps this trench/s runs a mile or more in length and perhaps in various degrees of depth. For this theory to be correct, there must exist multiple trenches of varying depths, with sea glass having to overcome multiple crevasses to get to the shore.
From speaking to lovely Seaham locals, during the 1990's, Seaham was abundant in large chunks of sea glass "all the colours of the rainbow" and only locals knew about it. Today, in 2026, it has become one of the world's most famous sea glass beaches, and for good reason. In fact, during the 1990's, it was not particularly en vogue to collect sea glass yet some people did and eventually the love grew and expanded globally. I have considered the idea that perhaps, like Fort Bragg in California and certain beaches in Cornwall, that the sea glass here should be protected from collecting. However, there will always be collectors and always people who will sneak some into pockets. It is just the human state and since we have been collecting rocks, shells etc for hundreds of thousands of years as a species, collecting is part of the hunter gatherer instinct innate in us all. It makes us feel safe and productive.
After all, sea glass is one of the only historical artefacts that the public get to find and keep. For me, that is what makes it so exciting and holds a special place in my heart, as a history lover.
To get justification on my theory, it would involve a dive team and if you have ever been to Seaham, you will know the tides, currents and power of the North Sea is not to be played with. It would be an unnecessary risk to life for any diver. To bypass this, perhaps an ultra strong underwater camera or drone could be used or LIDAR but I am no expert in these fields. I do own a small drone. At low tide when the weather is fairer, I will fly it over and record my findings when the beach is empty of people to see any evidence if this is possible. I'll update this post in the future.
What do you think? Do trenches filled with sea glass, multis, bubbles etc, exist in abundance? This leads me on to my next theory and one of the questions I get asked most in my jewellery making classes.
Will Seaham sea glass eventually run out?
The simple answer, all things considered, is yes.
But not how you might think. Whether the trench theory is correct or not, it is much more likely that the sea glass that exists in the sea currently at this moment, is ageing and slowly being ground away into slimmer and slimmer pieces. The threat is not predominately human collection, although it is a secondary reason for decimation, but simple time. Each second means less sea glass. If my trench theory is correct, then the pieces in the trenches there now are also grinding each other into dust and may never see the light of day on shore. However, I don't believe that we will see a true "die out" of sea glass for the next 30 years. I believe until then, based on the speed of sea glass give and take at Seaham, sea glass of today's quality will be exceptionally rare. However, that is not a reason to panic as it is just my theory.
Will Seaham multis be the future "Cairngorm Stones"?
For context, Cairngorm Quartz (a type of citrine, found only in the Cairngorm mountain ranges here in Scotland and Scotland's national gemstone, you can view them in our Glasgow shop) was a highly prized gemstone in the early 20th century and even features in the Crown Jewels. It has a wide variety of colours, from basically colourless to true citrine yellow to dark brown (most prized and exclusive, called Morian) but since mining became illegal, production of these stones has become even more sought after and exclusive. You will find plenty of fakes when looking for antique Scottish jewellery known as paste gems - essentially Cairngorm stones made of imitation glass paste or glass itself. Fake Cairngorm was created to duplicate the expensive originals like designer fakes, as a status symbol. True can also be said of Scottish freshwater pearls in today's market, now prohibited unless collected before 1998.
This being said, the original historical pieces can go for a pretty penny - will good Seaham multis be remembered in such a fond historical light? And will they appreciate in value as the stock gets rarer and rarer? I do believe to a certain extent this is true.
What do you think on the theories above? I am 100% open to options, thoughts and other theories.
Happy sea glass collecting!
Laura x
